Beatport Importer Userscript v1

This script currently supports importing;
* Release Title
* Release Label
* Release Catalog Number (if available)
* Release Date
* Tracklist

Note that Beatport's catalog information doesn't have join phrases, their web site merely adds a comma. I've opted not to include a join phrase for the moment.
Tested with http://www.beatport.com/release/stay-the-night/1187110 and http://www.beatport.com/release/dare-you-the-remixes-part-1-remixes-by-tiesto-vs-twoloud-and-cash-cash/1238454

/cc @murdos
Closes #18