Upgrade Gitlab to version 8.17.8
Use newest gowork infrastructure for gitlab SR
Upgrade Gitlab to use version 8.17.8 with required gitlab-shell version 4.1.1-1 and gitlab-workhorse version 1.3.0. Configurations and wrapper upgraded to work with the current version.
Set cors header directly in nginx configuration, so that it's not required to create custom slave frontend configuration to include Access-Control-Allow-Origin