Pretty-formatted URLs

[alastair]

We want to format entity names into URLs. Current plan is this:

http://dunya.compmusic.upf.edu/carnatic/artist/7d0561b3-4aef-4702-95da-3ebbda964d9a/artist-name

http://dunya.compmusic.upf.edu/carnatic/raaga/9/foo-bar http://dunya.compmusic.upf.edu/carnatic/taala/9/foo http://dunya.compmusic.upf.edu/carnatic/instrument/9/foo

Names will be lower-case, with spaces converted to -. When typing a URL, everything after the ID is ignored. We will use unidecode to remove diacritics from Raaga and Taala names to put in the URL.

[alastair]

This has to be done on both Carnatic and Hindustani