Use 'exec' in Unicorn and Sidekiq launch scripts

When running Unicorn or Sidekiq in the foreground this change removes
an intermediate /bin/sh process. This makes process supervision in the
GitLab Development Kit more reliable.

This change does not affect Omnibus-GitLab (because there we do not
use these launch scripts). Installations from source do use the launch
scripts but for the standard GitLab init script this change will not
make a difference.

Custom installations using Upstart or Systemd may be affected however,
because under certain configurations these systems count exactly how
many forks happen during process startup, and we are reducing that
number by one here.

Closes https://gitlab.com/gitlab-org/gitlab-development-kit/issues/116

See merge request !3964

Use Rugged's TagCollection#create instead of gitlab-shell's Repository#add_tag for better performance

This was originally opened at !1757 by @pcarranza but I changed it to use Rugged instead of gitlab_git, following @DouweM's request.

Once this is merged, https://gitlab.com/gitlab-org/gitlab-shell/merge_requests/26 will be mergeable too.

See merge request !3745

Fix typo in user steps feature file

Just came across a typo in the user steps file.

See merge request !3943

Update patch_versions.md with explicit --with statement for db gem group

## What does this MR do?
Updates `patch_versions.md`'s instructions on installing gems to explicitly install either the postgres or mysql groups.

## Are there points in the code the reviewer needs to double check?
No, but thank you for your time.

## Why was this MR needed?
I performed the steps listed in `patch_versions.md` and ran the command for updating postgres gems. Bundler told me at the end that it had not installed the postgres gem group, which caused the next step, migrating the DB, to fail for obvious reasons.

Changing the command to `--with postgres` made it install the postgres gem group, and db:migrate then passed.

## What are the relevant issue numbers?
None

## Screenshots (if relevant)
N/A

See merge request !3955

# Conflicts:
#	Gemfile.lock

Signed-off-by: Rémy Coutable <remy@rymai.me>

Use Rugged's TagCollection#create instead of gitlab-shell's Repository#add_tag for better performance
Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix group name font size in list

Somehow this css appears only in EE and makes group list inconsistent with other pages



See merge request !376

feature proposal issue template in contributing guide

This adds a feature proposal template to the contribution guidelines for internal and external use.

Fixes #15448 

cc @markpundsack @stanhu @dzaporozhets 

See merge request !3967

Enable LstripRstrip cop

This requires no code changes since it doesn't actually change anything in the codebase, just preventative.

See merge request !3959

Instrument methods used in email diffs

See merge request !4038

Remove unnecessary method call in events view

Since `User#to_param` already returns `User#username`, we don't need to
pass in the user's username. Changing this also helps us obey LoD.

See merge request !3996

Initialize wikis on legacy projects during check

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/4173

Helps https://gitlab.com/gitlab-org/gitlab-ce/issues/15423

See merge request !3931

Revert "Remove the Devise Async gem."

This reverts commit 1cc614f2.

It was causing the ActiveJob integration to fail, so unfortunately we'll have to add the gem again.

Resolves #17250.

See merge request !4027

Improve uniqueness of field names on the signup form

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15075

See merge request !3826

Make all of the nested constant instrumentation for core app code work
the same way, add mailer instrumentation, and add instrumentation to the
premailer gem.

Fixed username links in the performance guide

See merge request !4036

These would end up being rendered as:

    <a href="...">@yorickpeterse</a>
    <a href="...">@yorickpeterse</a>

[ci skip]

Fix a spec that was failing due to !3483

Spec were skipped in this MR so that tests started to fail in master
instead of in this MR!

/cc @connorshea @rspeicher 

See merge request !4033

Spec were skipped in this MR so that tests started to fail in master
instead of in this MR!
Signed-off-by: Rémy Coutable <remy@rymai.me>

Made it clearer that issue_id means iid, not id.



See merge request !4030

Set KRB5 as default clone URL when Kerberos is enabled and user is logged in

_Originally opened at !363 by @cernvcs._

- - -

In GitLab instances where Kerberos authentication (gitlab-org/gitlab-ee!6) is enabled, this protocol becomes the preferred one.

This merge request extends the functionality provided in gitlab-org/gitlab-ee!70 where Kerberos url is displayed alongside the SSH and HTTP urls when Kerberos authentication is enabled.

The implementation proposed here makes Kerberos the default clone procotol when Kerberos is enabled. When a logged in user visits the main page for a project or creates a new one, the first url offered is the Kerberos one.

This merge request also aligns the [implementation](https://gitlab.com/gitlab-org/gitlab-ee/blob/master/app/helpers/button_helper.rb) and [usage](https://gitlab.com/gitlab-org/gitlab-ee/blob/master/app/views/shared/_clone_panel.html.haml) of the 3 clone buttons, adds additional tests and updates some others to consider all the possible scenarios.

See merge request !372

Use sign out path only if not empty

Fixes: https://github.com/gitlabhq/gitlabhq/issues/10066

See merge request !3989

Update rspec-rails from 3.3.3 to 3.4.2.

This allows the removal of the monkey patch from this commit: 47ff1c56

It'll also make it slightly easier to upgrade to 3.5.0 later.

Changelog: https://github.com/rspec/rspec-rails/blob/master/Changelog.md#340--2015-11-11

See merge request !3999

Link to GitLab code review guide in contributing guidelines

I noticed that the contributing guidelines still link to the thoughtbot
code review guidelines even though we already have our own.

[ci skip]

See merge request !4018

This reverts commit 1cc614f2.

It was causing the ActiveJob integration to fail, so unfortunately we'll have to add the gem again.

Improve the Two-factor Authentication sign-in text [ci skip]

Resolves #14543.

See merge request !3483

Resolves #14543.

Add clear instructions on installing the pg_trgm extension

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/17191

See merge request !4025

[ci skip]

Added performance guidelines

Fixes #15254 #14277

See merge request !3303

[ci skip]

This removes several Spinach features and step definitions