BandCamp discovery

Originally this was done just to solve #483 and I've hooked it up to work on the main [discovery page][0]. 

Other stuff that has also gone is include:

- Tidied up state reference to determine "what" page/type of page the scrobbler is on
- Bound audio pause event to trigger reset (is this the correct thing to do???)

Examples of the various "types" of pages if you aren't familiar with BC

- [Album][1]
- [Compilation Album][3]
- [Track][2]
- [Discovery][0]

Just to note the only thing that doesn't work correctly is scrobbling a compilation track. This is wrong in previous versions though and never was solved. Other then just checking for a dash in the title which doesn't feel right IMO.

[0]:  https://bandcamp.com/discover
[1]: https://metamatics.bandcamp.com/album/instamatic
[2]: https://metamatics.bandcamp.com/track/neon-future-blue
[3]: https://noredseas.bandcamp.com/album/no-dead-seas-no-red-seas-vol-ii