Improve gitlab-sidekiq.service for GitLab v6.2.0 and above

[davispuh]

since GitLab v6.2 it added script/background_jobs for Sidekiq launching so we'll use it.

[axilleas]

While I like the idea of staying close to upstream, by making this change it would be more difficult to customize the paths if you'd like to follow the FHS and not use /home/git/. On the other hand I haven't given this much thought, any insights about this change?

[davispuh]

I don't see why using other path would be problem? Before, with current implementation you've to change it in 3 places (if you've gitlab elsewhere), now with this it will be 4 places to change, but that doesn't matter as it's in same file so simply "Find & Replace". Or if you mean you want log files in /var/log rather than with GitLab that would be feature request for GitLab itself to allow customize them.

[davispuh]

Changed script to bin dir because of GitLab changes with commit gitlabhq/gitlabhq@2341cef

I've been using this Systemd service for more than half a year and it works good ;)