Add new branch and tag action to tree dropdown

Right now, creating a branch or tag is only possible on the project page dropdown or on the commits page. This merge request both actions to the tree header dropdown. Now all repository web actions are available in this one location, plus the existing ones. It makes the operations a lot more intuitive.

## Existing Tree/Repository dropdown:

![Screen_Shot_2015-12-17_at_2.38.50_PM](/uploads/4d83a4b518093ea85f0859b385abcc7c/Screen_Shot_2015-12-17_at_2.38.50_PM.png)

## New Tree/Repository dropdown:

![Screen_Shot_2015-12-17_at_2.32.28_PM](/uploads/1fc18a511774630c5078a7d5c0fbb5b6/Screen_Shot_2015-12-17_at_2.32.28_PM.png)'

See merge request !2144

Remove duplicate entry in the changelog

/cc @DouweM 

See merge request !2149

Use gitlab-shell 2.6.9

See merge request !2143

Use gitlab-workhorse 0.5.1

Improves relative URL support.

See merge request !2134

Upgrade Poltergeist to 1.8.1.

Close #4131 

See merge request !2126

Fix ci_projects migration by using the value only from latest row [ci skip]

This is needed, because for some projects we have duplicate ci_projects.
This was introduced by lack of DB uniqueness on ci_projects.gitlab_id.

The MR fixes edge case by selecting value from latest.

/cc @yorickpeterse 

Fixes: gitlab-org/gitlab-ce#4123


See merge request !2133

Revert sidebar position for issue and merge request
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

cc @creamzy @skyruler 

See merge request !2132

This is needed, because for some projects we have duplicate ci_projects.
This was introduced by lack of DB uniqueness on ci_projects.gitlab_id.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fix ux issue with "This issue will be closed automatically" message

1. Make a nice box for "issue will be closed automatically" message
2. move it below emoji navbar. Otherwise looks wierd. 

Fixes #4134 

# Before
![Screenshot_2015-12-17_00.01.03](/uploads/2a24de77f76ce8a8b61ebabd3a02c83a/Screenshot_2015-12-17_00.01.03.png)

# After

![Screenshot_2015-12-17_00.03.08](/uploads/ccd21b87b7509e79773fabd179bef4aa/Screenshot_2015-12-17_00.03.08.png)
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !2129

Add info on using private Docker registries in CI



See merge request !2130

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Api support for requesting starred projects for user

Closes #4112

Note: probably targets the wrong release in the `CHANGELOG`, though 8.4 was not there yet

See merge request !2127

Move MR Builds tab next to Commits

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/4132

@dzaporozhets We've got two people who feel strongly about this now, @sytses filed an issue for it :)

![Screen_Shot_2015-12-16_at_22.19.35](/uploads/37e705610ba54e386928d7972398c247/Screen_Shot_2015-12-16_at_22.19.35.png)


See merge request !2128

Fix updating and disabling merge button when Merge Immediately is clicked

Fixes #4128

See merge request !2124

Fix Rubocop complain.

See merge request !2125

Fixes #4112

Clean up ci yaml doc

* Fix headings so that they are picked up by doc.gitlab.com
* Stick to 80 characters
* Clean up some examples

See merge request !2052

Update rerun to remove celluloid as dependency

After sidekiq 4 migration, we no longer need celluloid. `rerun` recent version also removed it from its dependency, so by getting this MR merged, we can solve #3797 

See merge request !2088

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Link to correct (source) project on MR builds tab

Used to link to `gitlab-org/gitlab-ce/commits/<branch-name>`, now links to correct project.

See merge request !2115

Temporarily disable Markdown caching



See merge request !2120

Fix headers of milestone and snippet show pages

Fix layout, and move "Edit" button to very right just like issue/MR.

Before:

![Screen_Shot_2015-12-15_at_17.33.20](/uploads/dbbeb6868b80e21894159126a0feca6a/Screen_Shot_2015-12-15_at_17.33.20.png)

![Screen_Shot_2015-12-15_at_17.33.28](/uploads/53d10b42adc34e48b063889120e9a746/Screen_Shot_2015-12-15_at_17.33.28.png)

After:

![Screen_Shot_2015-12-15_at_17.34.25](/uploads/b0d0ea3f6a7b61d51b474419207f7a02/Screen_Shot_2015-12-15_at_17.34.25.png)

![Screen_Shot_2015-12-15_at_17.35.55](/uploads/65b922f5249655d3733740690577c9d7/Screen_Shot_2015-12-15_at_17.35.55.png)

cc @skyruler 

cc @rspeicher 8.3 please!

See merge request !2104

Only cache markdown when object has been saved and has a proper cache_key.

See merge request !2119

Fix 'Merge Immediately' button

Fixes #4125

See merge request !2117

* Fix headings so that they are picked up by doc.gitlab.com
* Stick to 80 characters
* Clean up some examples