NULL ID3 tag strings info when not defined

[mikecarnohan]

Rather than displaying "Unknown Album" (or "Unknown Artist" or "Unknown Title"), sub missing strings for NULL, so that they appear cleaner in the app and on the streaming device. If all three are blank, sub the title for "Music Caster" and leave the others NULL for the stream display so that it looks clean. In that case, you can leave all as "Unknown" in the app, so the user is motivated to use the Metadata editor.

(Also, consider changing the order from Album, Title, Artist to Artist, Title, Album in the app, leaving the streaming display as it is.)