Use clock_gettime for all performance timestamps

This MR adjusts the performance monitoring code to use `Process.clock_gettime` (thus `clock_gettime(3)`) instead of `Time.now`.

Using `Time.now` / `Time.new` adds more overhead than `Process.clock_gettime`, it also doesn't provide a way of getting timestamps in nanoseconds (which `Process.clock_gettime` does allow).

See merge request !4899

Implement UI for new project page

## What does this MR do?

Updates the project creation page to conform with the latest UI updates.

## Are there points in the code the reviewer needs to double check?

Ney.

## Why was this MR needed?

Updated UI.

## What are the relevant issue numbers?

Closes #2542.

## Screenshots (if relevant)

**Desktop:**

![Screen_Shot_2016-06-18_at_04.00.48](/uploads/0313eee96a2aef9ed5e048989548b133/Screen_Shot_2016-06-18_at_04.00.48.png)

**Mobile:**

![Screen_Shot_2016-06-18_at_04.01.00](/uploads/505b110c3fcbf523aac08797db9f6781/Screen_Shot_2016-06-18_at_04.01.00.png)

See merge request !4766

Process.clock_gettime allows getting the real time in nanoseconds as
well as allowing one to get a monotonic timestamp. This offers greater
accuracy without the overhead of having to allocate a Time instance. In
general using Time.now/Time.new is about 2x slower than using
Process.clock_gettime(). For example:

    require 'benchmark/ips'

    Benchmark.ips do |bench|
      bench.report 'Time.now' do
        Time.now.to_f
      end

      bench.report 'clock_gettime' do
        Process.clock_gettime(Process::CLOCK_MONOTONIC, :millisecond)
      end

      bench.compare!
    end

Running this benchmark gives:

    Calculating -------------------------------------
                Time.now   108.052k i/100ms
           clock_gettime   125.984k i/100ms
    -------------------------------------------------
                Time.now      2.343M (± 7.1%) i/s -     11.670M
           clock_gettime      4.979M (± 0.8%) i/s -     24.945M

    Comparison:
           clock_gettime:  4979393.8 i/s
                Time.now:  2342986.8 i/s - 2.13x slower

Another benefit of using Process.clock_gettime() is that we can simplify
the code a bit since it can give timestamps in nanoseconds out of the
box.

Unused gon variable with very bad performance

## What does this MR do?

Remove an unused variable with a lot of performance penalty. It was opening a transaction just to return a constant string.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added

See merge request !4969

In any case if just want the value which is always ‘gitlab’

require 'benchmark/ips'

Project.first # To load database things
GitlabIssueTrackerService.first # To load database things

Benchmark.ips do |x|
  x.config(:time => 5, :warmup => 2)

  x.report("current") do
    Project.new.default_issue_tracker.to_param
  end

  x.report("") do
    'gitlab'
  end

  x.compare!
end

Calculating -------------------------------------
             current     4.000  i/100ms
                        30.938k i/100ms
-------------------------------------------------
             current     47.298  (±10.6%) i/s -    232.000 
                          4.366M (±20.9%) i/s -     17.202M

Comparison:
                    :  4366456.0 i/s
             current:       47.3 i/s - 92318.26x slower

docs: fix default_branch_protection default



See merge request !4479

Switched mobile button icons to ellipsis and angle

## What does this MR do?
Switches the mobile button icons

## What are the relevant issue numbers?
Closes #19170   
Part of #19200 

## Screenshots (if relevant)
![Screen_Shot_2016-06-27_at_9.08.28_AM](/uploads/7784489402e342e671d02b24d2ea0d64/Screen_Shot_2016-06-27_at_9.08.28_AM.png)


See merge request !4944

Resolve "Pin should show up at 1280px min"

## What does this MR do?
Decreased window min width for pinned sidebar

## What are the relevant issue numbers?
Closes  #19171    
Part of #19200 

## Screenshots (if relevant)
![Screen_Shot_2016-06-27_at_9.36.13_AM](/uploads/d0a87bca5af1bee808c5b1046c0ecf72/Screen_Shot_2016-06-27_at_9.36.13_AM.png)

See merge request !4947

Use GIT_DEPTH for builds

## What does this MR do?
Enables experimental feature to use shallow cloning. 

## Why was this MR needed?
To speed up the builds and reduce the pressure on NFS servers. This should save us between 30s to 1m of the time of each build.

## More information
 `GIT_DEPTH`: https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/merge_requests/188

## Problems
- Too small value for `GIT_DEPTH` can make it impossible to retry old changes.
You will see `unresolved reference` in build log.
We should then reconsider changing `GIT_DEPTH` to higher value
- Mechanism that rely on `git describe` may not work correctly when `GIT_DEPTH` is set. This will happen, because only part of the git history is present on the build machine

## Requirements
GitLab Runner 1.3.0. Currently all our internal runners use beta release or 1.3.0 with support for `GIT_DEPTH`.

@pcarranza Please decide when to merge that. We should start monitoring to see an impact on our NFS servers.

cc @jacobvosmaer-gitlab @pcarranza 


See merge request !4730

Add SMTP upgrade information

8.8 to 8.9 requires an update to the SMTP settings for source installs.

See merge request !4966

Closes #19252

[ci skip]

Refactor GitLab architecture document

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/14236

See merge request !3694

Display last commit of deleted branch in push events

## What does this MR do?

Display the last commit of a deleted branch in the push events of a project.

## Are there points in the code the reviewer needs to double check?

Is the change in `app/models/event.rb` the correct way to display a two-line event for deleted branches?

## Why was this MR needed?

It is easier to restore an accidentally deleted branch if the commit hash is displayed in the push events.

## What are the relevant issue numbers?

Fixes #18659

## Screenshots

### Before garbage collection

![before-gc](/uploads/5674cd53e1564d48b7f2f8406ea0fbed/before-gc.png)

### After garbage collection

![after-gc](/uploads/80950c1932feeb3b69d0fc11b8f7acf4/after-gc.png)

See merge request !4699

Fix encrypted data backwards compatibility after upgrading attr_encrypted gem

Adds missing attribute to attr_encrypted so it is fully backwards-compatible. Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19073

See merge request !4963

Add custom highlighting via .gitattributes

## What does this MR do?
Allows user control of language selection via a `gitlab-language` entry in `.gitattributes`

## Are there points in the code the reviewer needs to double check?
(paired with @stanhu)

## Why was this MR needed?
Guessing languages by filename is fraught and often wrong. In one project, `foo.pl` may be perl, and in another it may be prolog. Users might have a Thingfile that needs ruby highlighting, or depend on things that can't work in general, like `*.C` (capitalized) mapping to C++ instead of C.

This allows the user to override language choice so they never have to look at a mis-highlighted file.

## What are the relevant issue numbers?
https://github.com/jneen/rouge/issues/494
https://gitlab.com/gitlab-org/gitlab-ce/issues/13818 (*.tpl can't in general map to Smarty)
https://gitlab.com/gitlab-org/gitlab-ce/issues/13615 (in cases we don't have a language and mis-identify it, users could map to 'text' to turn off highlighting)

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added (N/A)
- [x] Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4606

Completed new project page

Updated CHANGELOG

Corrected 'Create project' button

Made responsive

Added gitlab export button

Changed Spinach test to match updated UI

reverted test changes and fixed UI

Corrected 'Repo by URL' text

Fixed static namespace style

Added errors partial

Added padding to bottom of page-with-sidebar

This reverts commit b435d7405364d28ec364072f4437512da2876762.

paired with @stanhu

Rename Licenses API to License Templates API

## What does this MR do?

Earlier I renamed this in EE, thinking license templates was an EE-only feature. This backports that change to CE. Thanks to @vsizov for pointing out this error.

See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/400 for the EE merge request. 

See merge request !4957