Don't run qunit task by default (instead require "grunt test").
New way to handle InvalidTargetErorr and WebRtcNotSupportedError

.. in UA.call() and UA.newMessage()

- Do now throw an exception but handle in Session and Message 'failed' event.
Love to console logs.
Merge branch 'master' of github.com:versatica/JsSIP

Conflicts:
	src/Session.js
Enhance JsSIP.Exceptions experience
Enhance JsSIP.Exceptions experience
Set a default value for stun_servers configuration parameter

-- Empty Array.
Do not raise an exception when UA is closed

.. and a UA method is executed
ua.call and ua.sendMessage: In case of invalid target, set a real JsSIP.URI instance to request.ruri rather than a string.
New test unit for testing JsSIP.UA.
Improved README example ('views' param in UA.call).
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/MediaSession.js
	src/UA.js