Fixing like / dislike trigger. Also updating the .alfredworkflow...

In addition to the the like/dislike trigger not working two of the action names were wrong in the workflow:

The arguments for next and previous in the triggers were "nextSong" and "prevSong", however the script expected the arguments "next" and "prev".  

I updated the script to mirror the applescripts which expected "nextSong" and "prevSong".

`if action = "prevSong"`  WAS `if action = "prev"` which didn't work.
`if action = "nextSong"`  WAS `if action = "next"` which didn't work.