All branches: run UI tests on Firebase Test Lab with Travis

[JoseAlcerreca]

There's a way to add the client secrets to travis, encrypting a file:

http://engineering.dailymotion.com/running-firebase-test-lab-on-travis-ci/

But I'm not sure about this particular implementation. after_success looks like the wrong hook to run UI tests unless we just want to warn about failures. Not sure how that'd work.

[oldergod]

As you said, I don't think after_success is the right one to run those tests.
I would rather run them as a simple extra step in the script list of commands and then use after_script to download the results via gsutil.

[JoseAlcerreca]

Apparently Travis is having problems at the moment. The CLI tool doesn't authenticate
travis-ci/travis.rb#448 and others