V2018

This MR makes the following changes:

1. Fixes test coverage
2. Includes MR !82 (merged) for GitLab webhook support.
3. Upgrades Syfony to 4.1.6 and resolves all symphony deprecations from 3.4 to 4.1.6 inclusive.
4. Compatibility with PHP 7.2
5. Improved Documentation
6. Other minor fixes.

I appreciate that this may benefit from being split and I'm happy to re-roll this without MR !82 (merged) but that would make !82 (merged) a prerequisite of this MR.