Revert "Merge branch 'git_hook_messages'"

At least the following things were broken:
- missing require for 'gitlab_access_status' in lib/gitlab_net.rb
- gitlabhq master internal API returns 'true' or 'false', gitlab-shell
  expects JSON

This reverts commit 11311a95545f967a5736cd16ab5fc37f7e658519, reversing
changes made to 45444597aef3e434571de2491934ae92357ad231.