Zeroconf and filesystem browser

The main changes in my mergable branch relate to #249 and touches on #30. I'm sure this wasn't quite where you were going with this, but I've added, primarily for my own use, some quick access to the zeroconf/bonjour/avahi activity. I find this a fairly quick way of operating multiple mpd servers from MPDroid. Even without storing or simultaneously using multiple connection settings, switching is quick and easy enough to provide a nice stopgap.

I use a script that I currently call mpd-enslaver to synchronise playlists and play states between mpd servers, and have another branch with functions particular to that setup. Those probably aren't suitable for general use, however, as the server setup is quite convoluted.