Add .travis.yaml for automatic run make check and make test

[evgeniysergeev]

We put a lot of effort into building the make check and make test commands to automatically identify errors like this. You would save a lot of trouble by running these a regular part of your workflow and taking the time to understand what causes them.

Originally posted by @pchote in https://github.com/OpenRA/d2/issues/140#issuecomment-538327412

[evgeniysergeev]

Blocked by #159 and #158