Hardcode some a default codec preferences

Hardcode some a default codec preferences

For video use H264 over Theora as it's better quality and there is
no reason to prefer a free codec if people already have the patented bits
installed anyway. Also prefer H263 as it's reasonable and it works around our
H263-1998 negotiation being slightly broken because of gstreamer :(

For audio prefer speex wideband over speex smallband and all other audio
codecs.

And in general disable various codecs that are not really suitable for use in
conferencing.

From: Sjoerd Simons <sjoerd.simons@collabora.co.uk>

svn path=/trunk/; revision=2567