website: change translation of models to lower case

Since the name of a model may appear in the middle of a sentence we
default it to lower case instead and use .capitalize to transform it
when it appears at the beginning of a sentence.
website: allow playlists to have sources outside Stoffi and be filtered by those sources in search
website: remove old cruft
website: create helper method to print 'no results' message
website: create folder for moving ads into partial views
website: insert ads in search page
website: style ad units