Improvement on progress bar and lots of bug fixes

Fixed so that if click forward/reverse track, will skip next track if it
is "processing for upload" so music continues to play uninterupted.
Added fade in/out transitions for waveform and album art images.
Fixed bug: toggle off commentview triggers unfavorite of track.
Fixed bug: last track of loaded feed finishes playing, progressbar
controls get messed up.
Fixed bug: if clicked pause on track while it was still buffering,
progress timer would continue to tick.
Track progress label now shows "buffering" right as new data is loaded.