Bug fixes
- #411: getContext() can return null in Fragments.
- #415: App crashes when pressing the album cover in player.
- #447: Fix all service notification issues.
- #484: Add error handling to SelectAlbumModel functions.

Enhancements
- #433: Lock screen playback controls should include next/previous track.
- #476: Remove jcenter().
- #477: Make all preference operations context-free.
- #485: Remove MusicService.
- #493: Introduce new Generic Fragments, ViewModels, and Adapters for the display of API data.
- #505: Implement server feature checking.
- #506: Convert all remaining Music servic classes to Kotlin.
