WebRTC/MediaHandler.js: add instance variable phonertc for plugin stuff
WebRTC/MediaHandler.js: remove peerConnection stuff from constructor
WebRTC/MediaHandler.js: add .phonertcSendMessageCallback, .phonertcCall
WebRTC/MediaHandler.js: setDescription calls into phonertc plugin
WebRTC/MediaHandler.js: better debug logging, this-binding
WebRTC/MediaHandler.js: make getDescription a no-op
WebRTC/MediaHandler.js phonertcSendMessageCallback builds SDP w/ cands
WebRTC/MediaHandler.js: getDescription succeeds w/ SDP after 2 seconds
WebRTC/MediaHandler.js: make mute-related functions no-ops
WebRTC/MediaHandler.js: getDescription forces a=setup:passive
WebRTC/MediaHandler.js: getDescription removes a=crypto lines

I was getting the following error from the calling desktop browser:

  Session error description: Cryptos must be empty when DTLS is active
WebRTC/MediaHandler.js: fix phonertc.role logic, this-binding