Bug 1025586 - MarionetteJS Tests for Smart Collections

This creates a simple framework for creating Everything.me tests. The test in particular stubs the Categories/list response, verifies that we can create a few smart collections and that they appear on the homescreen.

https://bugzilla.mozilla.org/show_bug.cgi?id=1025586
Setup is a bit tricky, getting the server URL before the client is ready is non-trivial. I'll look at a solution for this with james.