Initial commit... Implemented async events from webrtcConn in node addon
Fixed event numbers in initwebrtc
Used new async way to init webRTCConnection, new event codes
Changed way callbacks are handled, now are object specific
Changed name of the function to add callbacks
Fixed lock bug introduced by async
Updated ExternalOutput from master branch
Merge branch 'master' into async_events

Conflicts:
	erizo/src/erizo/WebRtcConnection.cpp
	erizo/src/erizo/media/ExternalOutput.cpp
	erizo/src/erizo/media/ExternalOutput.h
The callback for events in WebrtcConnection is now passed on init
Added stats hook
Added stats hooks to webRtcController
Added first implementation of connection statistics
Added jitter and lostpackets to stats
Unified rtp headers WIP
Moved all rtp related files to erizo/rtp
Using the headers methods instead accessing the variables
Added processing of SR RTCP packets for stats
Added id to stats
Changing direct access to variables to using the methods for rtpheaders
Added periodic stats report