Make users theme configurable

Fix API::MergeRequest

Corrects the update document to match the version of gitshell specified in the install document (1.7.1)

Change-Id: I02814fb47edcc915309183547cc8dcb165100f4f

GITLAB-1262

Change-Id: I690cb8ea294df53ebe8405a519c23c501af2c21a

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

Fixes #5144 Refs #4996

Added .ruby-version & .ruby-gemset in .gitignore

Drop support of root namespace in model

Don't show users password change page if ldap users

Fix issue_closing_regex in gitlab.yml.example

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

Update unicorn.rb.example

[WIP]Drop support of root namespace in routing

Add "public-project?" checkbox to new-project view 

Minor UI fix in views/public/project/index.html.haml