Bookprocessor list functionality

Updated realm to 0.76
Get  list of media files in users audiobook folder using mediacursor.
Renamed realm classes to have Realm prefix to avoid confusion.
Updated models

Some general additions to realm models and regular models.
Bookprocessor also slightly updated
Optimized imports
MediaMetadataRetriever to fetch audio metadata

Stop tracking idea folder and .iml files
Merge remote-tracking branch 'origin/dev'