Add GitLab CI build system support

[reicheltp]

I run my builds on GitLab CI and it would be awesome if there is 1st class support for this environment.

I will do a PR soon if nobody have any objections.

[gep13]

@reicheltp no objections from me 👍

[antwilliams]

Well this is good/bad timing (depending on your point of view)!

I'm just finishing off the test cases for my implementation of this. https://github.com/WarwickControl/cake/tree/feature/gitlab-ci

[gep13]

Ha ha :-D Great minds think a like!

Perhaps you and @reicheltp can work together to finalize the implementation, and then submit the PR.

@antwilliams this is part of the reason why in the contributing documentation we ask that you submit an issue before starting to work on a PR. That way, it reduces the changes of duplication of effort, and also effort on something that might not get pulled into Cake.

[antwilliams]

Oops, I missed that (first) step in the guide in my eagerness!

@reicheltp - do you already have an implementation for this functionality? I have just pushed (warwickcontrol/cake@3e9bfb70069d57d24ceadcd7d4d41b4246cba4ec) a completed implementation and test fixture for GitLab CI support.
I am just ensuring everything works correctly on a local GitLab installation and then I will create a PR. Let me know if you have anything to add to my code and I can add you as a collaborator.

[reicheltp]

@antwilliams Good that I've created an issue first, before starting to implement this. 😄 I will take a look on the PR now.

[antwilliams]

I've just rebased my PR based on the latest development branch, this includes the changes merged with PR #1222.

I notice that this ticket has been tagged as being part of the 0.17 release, I don't know when that is scheduled for but I am going on holiday tomorrow for a week. I won't be able to respond to any review actions until I get back.

[devlead]

Fixed by #1275