Handle no track being played in iTunes

* Sending the message 'STOPPED' from the AppleScript when player is
  stopped
* Displaying appropriate message to the user
Bug: Don't start iTunes when script runs unless it is already running

* Added function to AppleScript to check if a certain program is running
* Returning after sending message 'NOT_RUNNING' if iTunes is not running
Add -X option to less
Bug: Tracks with a hyphen in the name don't get searched properly

* Changed format of result returned by AppleScript (TODO: check if a
  JSON result can be sent out instead of this cooked-up version)
* Combined data validity check and parsing for artist and song