Soundcloud Integration

Issue #49 for soundcloud integration.

Soundcloud does not appear to assign unique IDs to songs, so for the FilmSnob ID attribute we used the username and track title from the URI to identify a song. For example, "theweeknd/the-weeknd-king-of-the-fall".
a similar thing was necessary for rutube and we solved it like this: https://github.com/maxjacobson/film_snob/blob/master/lib/film_snob/video_sites/rutube.rb#L5-L7

I'm not sure if either is better than the other, but I'd like them to be consistent. What do you think?