Submit Sync GitLab module for revision

Summary:
The first version of the Sync GitLab module. It still misses some cURL error
checks and has no abstraction layer.

Test Plan:
Create Account
Edit Account
Delete Account
Check each step with GitLab

Reviewers: m.iancu

CC:
Added @todo
Submit Sync GitLab module for revision

Summary:
The first version of the Sync GitLab module. It still misses some cURL error
checks and has no abstraction layer.

Added @todo

Test Plan:
Create Account
Edit Account
Delete Account
Check each step with GitLab

Reviewers: m.iancu

Reviewed By: m.iancu

Differential Revision: http://phab.code4fun.de/D84
Merge branch 'master' of https://github.com/KWARC/MathHub