Update 20111017 to Editor draft

The editor team put up a new version of the editor draft at 

http://dev.w3.org/2011/webrtc/editor/webrtc-20111017.html

Changes:

* Modified MediaStream() constructor to take a list of MediaStreamTrack objects instead of a MediaStream. Removed text about MediaStream parent and child relationship.

* Added abstract.

Thanks,

Adam on behalf of the editor team