Saucelabs support

This pull request is only so that we can do an internal code review. We will not get merge it, but send a pull request upstream.

@arunoda, we are adding Sause Labs support to travis-ci-meteor-packages. Would that be something you would be interested in merging in?
you can install if from here. Then `coffee` binary is available on `~./node_modules/.bin/coffee`.
BTW: I prefer if you use plain old JS :)