Bug 903152: Execute git tidy ops as gear user

Execute git tidy operations as the gear user. By running them as
the agent user, ownership of many of the git repo files is changed
from the gear user to root.

Resolve: https://bugzilla.redhat.com/show_bug.cgi?id=903152
Merge pull request #1199 from ironcladlou/bz/903152

Merged by openshift-bot