Enable `gitlab-ctl show-config`

Reassigned to @jacobvosmaer

We need this to be able to create wrapper scripts that use local configuration information such as the RAILS_ENV and the name of the gitlab user.

Done in !28 (merged). Unfortunately, gitlab-ctl show-config is not as useful as I hoped. It seems to only show configuration values which deviate from the defaults.

Status changed to closed

mentioned in commit 5ad7e8b8