Move js tests to `test/javascripts`
Latest ember
Latest ember-data
Introduce Sinon.js for spies, stubs and mocks
Defer App readiness until application view has loaded.

This provides finer control over readiness for testing.
Convert mocha tests to be client-side integration tests
Set`Ember.testing = true` in tests.

This prevents automatic scheduling of runloops. We also need to set `App.isInitialized = true;` to prevent `App.initialize()` from being scheduled. This probably shouldn't be necessary and should be addressed in Ember itself.
Minor test cleanup