Begin taggable feature

Members will be able to tag artists with arbritary tags such as 'Rock' or 'Seen Live' similar to last.fm's tagging functionality.
A thing.
Basic tagging.

Added basic tagging functionality to artist model and added Unique Constraints to Tag and TrackPosition.
Conifg change.

Added configuration for the default number of objects to return for models.Tag.top_artists, models.Artist.top_tags and models.Member.top_tags (two of which must be implemennted at this time).
Top tags for artists.

Top tags added for artists in models and schemas. Test added for some tag functionality. Silenced current schema test errors related to output.
Switch to GNU GPLv3

MutagenX is GNU GPLv2
Begin sluggable URL feature.

Eventually, this feature will mature into being able to use /artist/the+foo+bars/ instead of /artist/1/ in URLs
Begin slugurl features.
Name change. README update.
Slug URLs appear to be working.
Merged slugurls into dev.