[SAC] GitLab mirroring

[Sandro Santilli]

I was unable to find the "Repository Mirroring" section in the PostGIS
project configuration on OSGeo GitLab instance. The section should be
there according to
http://docs.gitlab.com/ee/workflow/repository_mirroring.html#existing-projects

Björn, or anyone else: could you figur out how would that be done ?
Ideally we'd have a project setup as a mirror of an SVN project
and using the trac external ticket tracker.

--strk;