Merge pull request #46 from jzelinskie/feature/recursive-label-model

Label foreign key -> self
Refactor Discogs API slightly.
Add routes for viewing artists, masters, and searching.
Add viewing artist view and write skeleton code for masters and searching.
Add viewing master view.
Basic template for viewing masters.
Discogs API no longer uses generators - update this in the tests.
Minor style tweaks from flake8.
One more style change from flake8.
Rename discogs api call results to "response".
Remove unused import pprint
Merge branch 'feature/music-profiles' into develop