Support GitLab API for self-hosted git hosting

[almereyda]

Similarily to #65, me as a user of coophub would like to connect this dashboard to a variety of GitLab communities on different servers, in order to achieve an aggregated higher-level view of the communities I am interacting with.

[chriscroome]

Wasn't this sorted out on issue #4 ?

[pbrudnick]

Wasn't this sorted out on issue #4 ?

Well, not really, we do support gitlab.com and git.coop using the gitlab base module (because they use the same API schema). You can check: https://github.com/fiqus/coophub/tree/master/lib/coophub/backends

If we want to support different public gitlab servers we should add different implementations of the gitlab module (like https://github.com/fiqus/coophub/blob/master/lib/coophub/backends/git_coop.ex and https://github.com/fiqus/coophub/blob/master/lib/coophub/backends/gitlab_com.ex).
At least, this is how it works now.

[sutty-coop]

Maybe something like this?

coop:
  source: gitlab
  host: 0xacab.org

So there's one source but you can add the hostname as modifier. It would support subdirectory installs ("0xacab.org/gitlab") but calling it "host" would be misleading.