Enable cgit caching.

* modules/openstack_project/files/cgitrc: Allow 1000 cache entries. Set
TTL for dynamic pages, repo summary pages, and the cgit front page to
one minute. Rely on the cache defaults for other pages. The various
options and their defaults can be viewed in cgitrc(5).

Change-Id: I49192b1ac43446a54b8ae98a44df5860bbafe1e0
Merge "Enable cgit caching."