IS-2: Create a wrapper for IMAP methods for unit tests purposes.
IS-2: Add unit tests for the method checkPassword.
IS-2: Add the ownCloud constants for backends.

Bad way but don't have another solutions at the moment.
IS-2: Add unit tests for unused methods.
IS-2: Remove the boolval method because it isn't compatible with PHP 5.4.
Merge pull request #5 from minidfx/feature/IS-2

Feature/is 2