Tagging of songs

We're only going to support a limited amount of tags, this should reduce the amount of duplicated tags
- Bagger
- Rock
  - metal
  - punk
  - hardcore
  - grunge
  - post-rock
  - classic rock
- pop
  - 70s
  - 80s
  - 90s
  - New wave
- electronica
  - ambient
  - dance
  - hardstyle
  - hardcore
  - jump
  - drum&bass
  - dubstep
- hip-hop
  - nederhop
- klassieke muziek
