Initial owners file for talk/media/webrtc/.

Including pthatcher@webrtc.org (already root owner) and
mflodman@webrtc.org.

BUG=
R=juberti@google.com, juberti@webrtc.org
TBR=juberti@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/15679008

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6425 4adac7df-926f-26a2-2b94-8c16560cd09d