Bug 1108874 - Create a loader for MarionetteJS Actions +autoland

https://bugzilla.mozilla.org/show_bug.cgi?id=1108874
This would fail because I don't set `this.actions` in the instance (or I miss it although I just scanned the code again). I encapsulated the class, not the instance. So you should consider to register one for this case to prevent errors.