[models] use constants for column names
[models] added Disc support
[Track] added date/original_date
Merge branch 'master' into adapter-scratchpad

Conflicts:
	kanihi/src/main/java/net/cjlucas/kanihi/data/DataStore.java
[DataSource] added shared instance
Merge branch 'master' into adapter-scratchpad
added count of tracks to list