gitlab: Upgrade to 8.5 + ...
- GitLab Software + patches ported to latest stable GitLab 8.5.1 (including fix for raw downloading to work in browser for private repositories);
 - Sync-with-upstream procedure streamlined (now only 1 branch for tracking upstream configuration files);
 - Base software upgraded: Ruby, Redis, Nginx, Git;
 - misc fixes.
 
Demo instance: https://softinst62804.host.vifib.net