added test class for DBManager
set up in memory Realm for testing
created generic method to create data to test
completed test on import for Tracks
completed import test for Mixtape
fixed test for import of videos
added category to DBManager to access featured import methods, tested featured tracks import
inhibiting warnings of retain cycle in DBManagerTests.m
added FIXME note
Merge pull request #2 from mcharite/feature/UnitTestDBManager

Feature/unit test db manager