Changed wording in application.rb and gitlab.yml.example to match unicorn.rb. This is for when using a non-root path

Change-Id: I02814fb47edcc915309183547cc8dcb165100f4f

GITLAB-1262

Change-Id: I690cb8ea294df53ebe8405a519c23c501af2c21a

Conflicts:
	app/models/user.rb
	config/initializers/1_settings.rb
	spec/models/user_spec.rb

It turns out that regex escapes and YAML quoted-scalar escapes don't play
nicely together.

Any mention of Issues, MergeRequests, or Commits via GitLab-flavored markdown
references in descriptions, titles, or attached Notes creates a back-reference
Note that links to the original referencer. Furthermore, pushing commits with
commit messages that match a (configurable) regexp to a project's default
branch will close any issues mentioned by GFM in the matched closing phrase.
If accepting a merge request would close any Issues in this way, a banner is
appended to the merge request's main panel to indicate this.

Ref: https://github.com/gitlabhq/gitlabhq/commit/e6159b8725f99af78f446f8d33fa0e52b7780430
Ref: https://github.com/gitlabhq/gitlabhq/pull/3204
Ref: https://github.com/gitlabhq/gitlabhq/issues/1228

Add Rails' variable in application.rb to support relative url

This variable is used by assets compilation and other modules.

Note that user needs to change application.rb too

Restrict session cookie to the relative path if set.

Ref: https://github.com/gitlabhq/gitlabhq/commit/2c2f1e31856a4decdae469974f5bea8245316f7e

Fix Update attachment_uploader.rb bug with relative URL

See: https://github.com/gitlabhq/gitlabhq/commit/161afda3fa4fca58f396e9c3acbd72bc14490ace

Fix Wall relative bug with attachement files (javascript)

Change-Id: I73b4aa4c46afd56ae02fb24abcd673c0724547e4

Jira issues numbering format are like: "PROJECT-1234".
Changed the regular expression to support Jira issues linking, in addition to the normal #123.

Added Jira Issue tracker configuration example

“Can create groups” and “Can create teams” had hardcoded defaults to
`true`. Sometimes it is desirable to prohibit these for newly created
users by default.

Conflicts:
	config/gitlab.yml.example
	config/initializers/1_settings.rb

This option allows to disable users from changing their username.

This is very usefull in environments using strong internal authentication methods like ldap, pam or shibboleth.

You can allow users to change theyr username in these environments, but then new users (users loging in first time) is blocked from gitlab is her username exists.