GitLab health check
Dev: https://dev.gitlab.org/gitlab/gitlabhq/issues/2109 Zendesk issue: https://gitlab.zendesk.com/agent/tickets/16311
Customer requested we add the ability to use http for health checks where a response to users says 'out of service' while they work on the box. => leave this for later
Sytse's note: use health_check gem, override with .outofservice file => leave this for later
use default url of the gem (/health_check IIRC)