Add a ToastReceiver on the UI-thread that listens for toast-able
messages from the back end.

Add robolectric to testing suite (for android-specific code).
Upgrade to gradle 2.1.
Make travis only run tests, not package.
Merge pull request #71 from trhodeos/tr.fix-toast

Add a ToastReceiver on the UI-thread that listens for toast-able
wip