Added top_hottt method to get hottest artists.

Also cleaned up some dupe code by refactoring VCR calls in spec.

Tweaked guard file to get autorun working again on my system. For some
reason the previous config wasn't re-reunning specs on file
modification.
Tweak spec to work with new format VCR options
Merge pull request #34 from subimage/feature/add-artist-top-hottt

Add top_hottt for artists