Remove the default RTP module.

This CL removes the default module owned by ViEEncoder, functionality in
the module to register default modules and the final changes in
rtp_rtcp_impl using default/child modules.

BUG=769
R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/42509004

Cr-Commit-Position: refs/heads/master@{#8514}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8514 4adac7df-926f-26a2-2b94-8c16560cd09d
10 files changed