Disable gitolite auto update option

Created by: marfillaster

Since gitlab does not have yet the full capability of managing complex repository and branch security, I suggest to have an option maybe in gitlabhq.yml to disable gitolite config auto update.

I kept on reverting my gitolite config because of this behavior every time I manage user permission in gitlab admin.

Another alternative is to have an expert tab where an admin can fully edit gitolite config file. Adding public key should commit though.