RTPSender and Receiver integrated in document

Hi,

attached is a part of a WebRTC 1.0 draft with RTPSender and RTPReceiver 
added to allow review in context. I'm not sure it is 100% aligned with 
Justin's latest version of the Pull Request [1], but should give an idea 
of how it will look.

Justin will have a presentation on the subject tomorrow, see agenda at 
https://www.w3.org/2011/04/webrtc/wiki/October_30_-_31_2014

Stefan

[1] https://github.com/w3c/webrtc-pc/pull/3