Improved styling of voting buttons to make it more obvious which vote has been selected.
Fixed incorrect styling in case when user did not vote.
Merge branch 'stage1' into voting-style

Conflicts:
	client/critiquebrainz/templates/review/entity.html
Updated styling after merging.
Updated musicbrainzngs dependency.
Added wrapper for get_artist_by_id in musicbrainzngs.
Created artist page.
Adjusted containers on artist page to properly display cover art images with various proportions.
Linked albums on artist page to album pages.
Linked home page and album page to artist.
Removed width from cover-art-container class which caused display problems on large devices.
Added pagination support for artist pages.
Adjusted style of releases grid a bit.
Changed default limit on artist page.
Added link to artist on review page.
Merge branch 'voting-style' into stage1