Add tests for mysql container

[vrutkovs]

Add minimal tests for MySQL container. This uses Travis CI to build a container and run ctf-cli-based tests on container.

Tests will help us check that new commits/PRs don't break functionality.

[bkabrda]

Hi, thanks for this PR. I've been planning some general setup for CI for all Dockerfiles in this repo (which would involve only testing those that were modified in git push or in a PR to not overload the CI :)).
The thing that's keeping me from doing that is the unclear relation between Fedora-Dockerfiles and the upcoming Fedora dist-git for Dockerfiles [1].

The discussion is going on at [2](originally, I just wanted to introduce myself as a maintainer of this repo :)) and the outcome may even be that this repo will be "dissolved" into dist-git repos and canceled altogether. (That also means that I'm not sure how the tests would be invoked during the build - please follow that conversation and contribute if you're interested).

So I'll keep this commit unmerged for now until the situation gets clearer.

[1] https://fedoraproject.org/wiki/Changes/Layered_Docker_Image_Build_Service
[2] https://lists.fedoraproject.org/pipermail/cloud/2015-October/005901.html

[vrutkovs]

Okay, agreed. I'll be writing some more tests for other Dockerfiles meanwhile, until CI/repo situation is resolved.