Add Local Update Hook
Rebased version of add_local_update_hook branch
https://github.com/gitlabhq/gitlab-shell/pull/85
Conficts: gitlab_projects.rb big changes in create_hooks
Rebased version of add_local_update_hook branch
https://github.com/gitlabhq/gitlab-shell/pull/85
Conficts: gitlab_projects.rb big changes in create_hooks