adds ProjectView#changeVideo(), a callback function to switch the youtube src in the iframe
changes the artists download method in festivals#login to extract the name of their hotttest song
changes the festivals#show view to put their hit song's name in their 'listen' link elements
Merge branch 'master' into youtube_works
Merge pull request #35 from paopay/youtube_works

Youtube works now - have to visit festivals/login in browser to reload artist list and extract the new data