src/WebRTC.js: WebRTC.isSupported = true, always
Gruntfile.js: tell jshint "cordova" is a global
WebRTC/MediaHandler.js: getDescription calls phonertc.call, logs info
WebRTC/MediaHandler.js: move sendMessageCallback into own function

Don't log candidates twice
WebRTC/MediaHandler.js: getDescription succeeds with SDP w/ candidates

Since the PhoneRTC plugin returns candidates asynchronously, I arbitrarily
chose to wait 2 seconds for them to arrive before succeeding with the generated
SDP.