Improve pipeline processing

## What does this MR do?
This works on top of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5295 trying to solve some edge cases introduced by that Merge Request. The fix switches to a state machine which is already a part of `Ci::Pipeline` and uses events with conditional transitions to switch between pipeline states.

This is approach is much more bullet proof and much easier to understand than a previous one where we were calling a `reload_status!` which manually updated `status`. Previous approach become confusing and prone to number of errors.

## Why was this MR needed?
This improves changes introduced by https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5295

## What are the relevant issue numbers?
None, yet.

## Screenshots (if relevant)
Not needed.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added (not needed since changelog for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5295 is already introduced)
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added (not needed)
- Tests
  - [x] Added for this feature/bug (most of tests do cover the triggering of Pipeline)
  - [ ] 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)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5782

# Conflicts:
#	app/models/ci/pipeline.rb
#	app/models/commit_status.rb
#	app/services/ci/create_pipeline_service.rb
#	spec/models/ci/pipeline_spec.rb

Corrected links/usernames in performance guide

## What does this MR do?

This fixes two broken links in the performance guide and removes the mention of Josh as he no longer works for GitLab.

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

No.

## Why was this MR needed?

The guide contained two broken links, and Josh no longer works for GitLab.

## What are the relevant issue numbers?

None.

## Does this MR meet the acceptance criteria?

- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] 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 !5772

Not sure if this is the right fix...
Or maybe we should actually merge:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5782

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13823349

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13671791

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13672004
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13810498

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13811203

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13810945

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13810811
And other similar places.

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5620#note_13810778

Remove unused SpamReport model; this was renamed to SpamLog

See merge request !5778

Resolve "New pipeline auto-completion"

## What does this MR do?

Add auto-completion to new pipeline.

## What are the relevant issue numbers?

Closes #19725 

See merge request !5389

update CHANGELOG

add auto-completion into pipeline

add auto-completion into pipeline

add auto-completion into pipeline

update changelog

modify tests

remove empty lines

add auto-completion into pipeline

update changelog

modify tests

switch text_field_tag into text_field

add test to new field

switch context into describe

Update CHANGELOG

render only commit title

update CHANGELOG

add auto-completion into pipeline

add auto-completion into pipeline

add auto-completion into pipeline

update changelog

modify tests

remove empty lines

add auto-completion into pipeline

update changelog

modify tests

update changelog

Update CHANGELOG

add indetation

add tests to pipeline ref

change file name for tests

change file name for spec tests

remove empty line

rename test it

rename test name

removing unexpected changes

removing unexpected changes2

update changelog

Update gitlab-shell to v3.3.3

Finishing touch for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5542

![](https://gitlab.com/gitlab-org/gitlab-shell/uploads/bd0d4864f7bd864d38bfb6798fdd4ea3/image.png)

See merge request !5780

Upgrade Rails to 4.2.7.1 for security fixes.

Upgrades Rails from 4.2.7 to 4.2.7.1 for security fixes.

For more information: http://weblog.rubyonrails.org/2016/8/11/Rails-5-0-0-1-4-2-7-2-and-3-2-22-3-have-been-released/

This should be backported to all currently-supported releases.

See merge request !5781

More information available at: http://weblog.rubyonrails.org/2016/8/11/Rails-5-0-0-1-4-2-7-2-and-3-2-22-3-have-been-released/

Merge request link after pushing

## What does this MR do?
Add API to generate new merge request urls if it is a new branch. The API will be called by gitlab-shell 

## What are the relevant issue numbers?

#18266 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] API support added
- 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 !5542

Use Ruby 2.3.1

## What does this MR do?

This WIP MR will eventually introduce 2.3 as default language for GitLab CE/EE

## Why was this MR needed?

@connorshea wants to be prepared for Rails 5.0, so we need Ruby > 2.2, so why not go 2.3 already?

## What are the relevant issue numbers?

Closes #12507 

## TODO

- [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] All builds are passing
- [ ] [Omnibus uses 2.3.1](https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/847)

See merge request !4948