add individual service definitions
fix MusicServices proto rel
export upnp wrappers @ .Services
add volume, muted, and previous calls
second update...

1. better error checking... i was trying a whole bunch of different
media formats, interaction scenarios, etc., and think i finally have
all the bulletproofing in place@

2. on my system, albumArtURI always comes back as a URI not a path -
also i moved the DIDL parsing to a seperate function so it can be used
in other places (like my code!)

3. add track position and duration. duration is accurate. position
appears to be updated every 5s.

4. added functions to get/set the name of the speaker, the play mode,
skip to a location, and flush the queue.
rename volume/mute fetch to getXYZ, getMuted returns boolean
botched two...
allow string argument to setMuted (in case caller is testing things like (!param)
didn't test that one… (sorry, too many pans in the fire!)
Merge branch 'services'
Merge branch 'master' of github.com:mrose17/node-sonos
lint and fix albumArtURI typos
contributors, licence, bugs & repo in package.json
position and duration in seconds
add albumArtURL to .currentTrack() response
remove TODO.md

TODOs now kept as issues on GitHub