increase size of image to 300px

300px accommodates larger album art
more ideas
major refactoring; new features

* new current_song_data var to store state
* song_data -> new_data
* check for actual message in response
* detect for song change
* remove fixNowPlayingData
* fetch larger artwork from iTunes music store and store in new
  albumart_hires attr
* time -> display_time
* etc.