Add basic syntax highlighting to cgit

 * modules/cgit/manifests/init.pp: Add highlight package
dependency to cgit server

 * modules/openstack_project/files/git/cgitrc: Enable syntax
highlighting option

 * modules/openstack_project/files/git/openstack.css: Add basic
syntax highlighting, copied from CSS that used to ship with
cgit by default

Closes-Bug: #1228361

Change-Id: Ic496215b5782527ac8159dedf639e549debeed2b
Merge "Add basic syntax highlighting to cgit"