New feature: Ability to leave project

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Refactor user associations. Drop support of Group#owner_id

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Remove User#namespaces method from code

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'feature/leave_project' of /home/git/repositories/gitlab/gitlabhq
More entries to changelog

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Look for project description during search

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

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