Handle new 'cv' argument from Anki 2.0.13.
Changed the value returned by .meta() depending on if the client is 2.0.12 or 2.0.13.

Also, fixed a change in rest_app.py that broke the unit tests.
Bump version to 2.0.2.
Respond to GET requests at the top-level of the REST API with the version of the AnkiServer (useful for checking connections).