Partially fixes Bug #40 : Added check to see if part of set to scrape the track listing
#40 bug fixes on Soundcloud; sounds and playlists are now found both in stream and sound mode

Original play button selector excludes play log, it was picking up the
play button in the recently played log (which uses the medium btn
class).
With no API to readily extract the current song, each case (playlist in
stream mode, individual sounds and playlists) are now picked up.
Merge pull request #50 from sonakpatel/soundcloud-set-bug

Soundcloud set bug #40