Adds files per commit, created/deleted/compare to hook data.

Switches gitlab_git to forked version; uses quick_diffs to get hook files.
Adds Gemfile ref to gitlab_grit forked version (used by gitlab_git).
Increased web hook timeout from 10s to 60s.
Adds case-insensitive sort to tree views.
Disables automatic merging of merge requests. (*)

* With no control over the commit message, we really don't want to accidentally
click the button. Disabling for now.