preliminary similar-tags stuff

Started coding for finding similar songs by comparing tags semantically
(added func to get similarity measure from
http://talisker.d.umn.edu/cgi-bin/similarity/similarity.cgi and
appropriate view to views.py) added a sample perl script for computing
semantic similarity with wordnet  (instead of using
http://talisker.d.umn.edu/cgi-bin/similarity/similarity.cgi like
currently) to tie in later; added and started template for
semantically-similar tag/song finding