-----
- Fixed a bug with the functions not sending the data to the server in the
correct format.
- Changed ``FlaskSplit.ab_test`` to take the alternatives as a single list
argument (i.e. ``ab_test('exp', 'a', 'b', callback)`` -> ``ab_test('exp', ['a',
'b'], callback)``).
- The callback to ``ab_test`` will now be called also when the request fails. In
this case the first argument is undefined and the second argument is the
jQuery response object.