Move mergablility check to Gitaly

Closes gitaly#889

See merge request gitlab-org/gitlab-ce!20019

Fix: Serve favicon image always from the main GitLab domain to avoid issues with CORS

Closes #47802

See merge request gitlab-org/gitlab-ce!19810

Merge branch '47631-operations-kubernetes-option-is-always-visible-when-repository-or-builds-are-disabled' into 'master'

Operations and Kubernetes option should be omitted when repository or builds are disabled

Closes #47631

See merge request gitlab-org/gitlab-ce!19835

Bump rugged to 0.27.2

See merge request gitlab-org/gitlab-ce!20026

Merge branch 'blackst0ne-rails5-found-new-routes-that-could-cause-conflicts-with-existing-namespaced-routes' into 'master'

Resolve "[Rails5] Found new routes that could cause conflicts with existing namespaced routes"

Closes #48010

See merge request gitlab-org/gitlab-ce!20015

Refactor the profile preferences docs

See merge request gitlab-org/gitlab-ce!20031

Docs clarify API to share project to a group

See merge request gitlab-org/gitlab-ce!19301

Resolve "Unable to install Prometheus on Clusters: 'Error: Chart incompatible with Tiller v2.7.0'"

Closes #48126

See merge request gitlab-org/gitlab-ce!20010

Add note about Master/Maintainer role

See merge request gitlab-org/gitlab-ce!20028

Rails5 fix Admin::HooksController

Closes #48142

See merge request gitlab-org/gitlab-ce!20017

Resolve "Set the language setting to something other than English, the branch of Merge Request will not be visible."

Closes #48100

See merge request gitlab-org/gitlab-ce!20016

Add docs for the cleanup step of a background column type change

See merge request gitlab-org/gitlab-ce!20020

Rails5 fix  expected: 0 times with any arguments received: 1 time with…

Closes #48141

See merge request gitlab-org/gitlab-ce!20018

Use Go 1.10 for source installations

Closes gitaly#1231

See merge request gitlab-org/gitlab-ce!19989

Use gitaly for backup rake task

See merge request gitlab-org/gitlab-ce!19742

Release notes: https://github.com/libgit2/libgit2/releases/tag/v0.27.2

Rails5 fix expected: 1 time with arguments: (97, anything, {"squash"=>false}) received: 0 times

Closes #48104

See merge request gitlab-org/gitlab-ce!20004

Rails5 fix Projects::PagesController spec

See merge request gitlab-org/gitlab-ce!20007

More gitaly disk access blocks

See merge request gitlab-org/gitlab-ce!19892

Implement filtering by filename on code search

Closes #43627

See merge request gitlab-org/gitlab-ce!19509

Move git version detection to gitaly for usage ping data

Closes #48105 and charts/gitlab#530

See merge request gitlab-org/gitlab-ce!19993

Rails5 fix  expected: 0 times with any arguments received: 1 time with arguments: DashboardController

Resolve "[Rails5] expected "2018-05-07 13:53:08 UTC" to be an instance of ActiveSupport::TimeWithZone"

Closes #47959

See merge request gitlab-org/gitlab-ce!20000

Operations and Kubernetes items are now omitted in the sidebar when repository or builds are disabled

Point out the specific anchor inside the document

See merge request gitlab-org/gitlab-ce!19998

LFS changes are detected by Gitaly

Closes gitaly#935

See merge request gitlab-org/gitlab-ce!19995

Updated horizontal ellipsis icon for text-expander

See merge request gitlab-org/gitlab-ce!18793

Closes https://gitlab.com/gitlab-org/gitaly/issues/889

Correct cURL syntax

See merge request gitlab-org/gitlab-ce!20014

Since Rails 5.0 the new framework has been added. It's called ActionCable.
It brings WebSockets support to rails applications.
By default the mountpoint of WebSocket requests is `/cable` [1].

GitLab allows using top level names as namespaces or usernames.
For example, `gitlab.com/cable` at this moment leads to a user with the
nickname `cable`.

This commit changes ActionCable's mountpoint to a reserved top level
word `-`.
This is just a stub and should not be be used in real work.

Please set correct mountpoints for each environments when configuring
ActionCable for real using.

[1]: https://github.com/rails/rails/blob/5-0-stable/actioncable/lib/action_cable.rb#L38