Facia tool test

Add unit (? or maybe end-to-end) tests for facia-tool.

The backend is mocked and tests check that user actions call the API with certain parameters.
The action tested are:

* Drag an article from latest to a collection and to a collection with groups
* Reorder articles inside a collection
* Move an item from a collection to another
* Add meta data (like isBreaking)
* Delete articles
* Publish a draft version

All tests run in karma + jasmine + phantom through grunt, no need to run scala or control actual browsers.

There's only one file changed in the code, `droppable.js`, this module now exports the drag events listeners so that test classes can trigger fake events.