Fixed acceptance test to account for recent changes in subscribe feature.
Revert changes in 57e31faffb7cf0904654a791464b0a58d5fccc4b

The angularjs client cannot start "quick reading mode" or "open all entries mode" until the AJAX response with the user data has been received.
Renamed /api/user_data route to /api/user_config

It's more descriptive of its actual function, specially since I'm gonna get the count of subscribed feeds out of the response for that route and into a new /api/user_data route.
Added controller and route to retrieve data about the user.

This way, the old /api/user_data route and controller action has been separated:

- /api/user_config returns the configuration set by the user. It should be enough to load this on app initialization
- /api/user_data returns other data about the user; currently only the total number of subscribed feeds is returned, but it is envisioned that other data will be returned in the future. This can be loaded when this data has potentially changed; e.g. after a feed subscribe job finishes successfully.
Complement the changes in 47b69ebdcf6e48abc02a69e9ed447e8c3d5e6703 making the corresponding changes in the angularjs client.

Obtaining user config and obtaining other user data has been separated into two different angularjs services. Both are invoked when initializing the app, but after successfully subscribing to a feed only user data is loaded again, to get the new count of subscribed feeds (which is displayed in the start page).

This fixes the circular dependency error, hopefully for good this time.
Reorganization of tests.

Moved some tests related to subscribing to feeds from the acceptance tests to the unit test for the User model. In the process some tests which were duplicated were deleted.
WIP: acceptance tests for the new implementation of the subscribe feature.