Added option to hide track/artist when Spotify is not playing. Changed m...

Hi Paul,

I took the liberty to add a feature I missed: to hide the track/artist whenever Spotify is not playing. I added a second menu item to toggle this behavior. Since both menu items are now actually feature toggles, I changed them to have a checkmark when enabled. Seems a bit more intuitive to me than changing the text of the menu item. Anyway, just wanted to share this. Thanks for your effort, this little app was just what I was looking for!