Backport two commits from EE

Backport part of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/110

See merge request !2424

Fix cross-project reference clipboard text

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2339

See merge request !2420

Update mailroom/postfix documentation [ci skip]

I worked with a customer to troubleshoot some strange Postfix and Mailroom issues. These doc updates aim to help other users avoid the same confusion.


See merge request !2430

Various UI fixes

* Fix missing padding for user/group pages
* Fix align of clone panel
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !2433

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

Add builds API

References #4264

See merge request !2207

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

Add pagination headers to already paginated API resources

Following #3045, I've added pagination headers using already available Kaminari methods.

## Pagination headers in action

![Screen_Shot_2016-01-14_at_12.14.53](/uploads/88807f754dd9aafbb24da85f6bdf9521/Screen_Shot_2016-01-14_at_12.14.53.png)

---

I've also added a shared example to test paginated API resources.

A possible next step would be to paginate all the API resources that return an array.

See merge request !2426

Import GitHub wiki into GitLab

Closes #2834 

GitHub doesn’t apply any constraints to theirs wiki slug allowing chars like ,, :, *, etc, we need to remove our constraints or some wiki pages will not be available after they are imported.

Some wikis use the Gollum's tags to link its internal/external resources like: images, urls, wiki pages, etc. So, to avoid that wiki links/images displays completely broken after they were imported, we added a new `WikiPipeline`, that for now will parse only simple links, and image tags.

##### Before `WikiPipeline`:

![Screenshot_2016-01-11_20.14.48](/uploads/46fd5dbb5acfc70aa8ecca3050b675e4/Screenshot_2016-01-11_20.14.48.png)

##### After `WikiPipeline`:

![Screenshot_2016-01-11_20.15.56](/uploads/b1d94aa852f385f867a7868c358b4257/Screenshot_2016-01-11_20.15.56.png)

See merge request !2324

Unsubscribe from thread through link in email footer

Closes #3437 

![Screenshot_from_2015-12-11_15-35-06](/uploads/cfb3d8737d4757f527995411f103d0ce/Screenshot_from_2015-12-11_15-35-06.png)

![Screenshot_from_2015-12-11_15-35-56](/uploads/9b7121be7ce4b05e5995ca6d38c5bea4/Screenshot_from_2015-12-11_15-35-56.png)

See merge request !2068

Standartize buttons and fields size

Fixes #8069 and #8070

See merge request !2428

Since GitHub doesn’t apply these constraints to theirs wiki slug
allowing characters like `,`, `:`, `*`, etc, we need to relax our
constraints or some wiki pages will not be available after they were
imported.

For an example the Devise project have a wiki page with the following
slug: “How To: Add sign_in, sign_out, and sign_up links to your layout
template”

fixes bug with commenting on merge requests



See merge request !2415

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

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

Add browser for build artifacts

Discussion in #3426, closes #3426.

See merge request !2123

* master: (51 commits)
  Fix version
  Fix specs and rubocop warnings
  Improve the consistency of commit titles, branch names, tag names, issue/MR titles, on their respective project pages
  fixed LDAP activation on login to use new ldap_blocked state
  Fix Admin/Users view to position buttons without spacing magic
  Update to Go 1.5.3
  Fix the undefinded variable error in Project's safe_import_url method
  Update CHANGELOG [ci skip]
  Add some cosmetic changes to variables API documentation [ci skip]
  Fix misaligned edit button in milestone collection partial
  Update button styles for Milestones#show
  Modify builds API documentation style [ci skip]
  Modify :ci_variable factory
  Ensure the API doesn't return notes that the current user shouldn't see
  Add 'Build' prefix to Variables entry name in API docs index
  Fix some typos
  Add spec for Note#cross_reference_not_visible_for?
  Remove (invalid) timestamp formatting
  Move `BroadcastMessage#status` to a helper since it's presentational
  Update CHANGELOG
  ...

Conflicts:
	doc/api/README.md
	lib/api/api.rb
	lib/api/entities.rb

Add variables API

References #4264 

See merge request !2264

Added also a `Gitlab::Ci::Build::Artifacts::Metadata::ParserError`
exception class.

[ci skip]