DO NOT MERGE: Work around several issues with non-compliant RTSP servers.

In this particular case these RTSP servers were implemented as local services,
retransmitting live streams via a local RTSP server instance.

They picked wrong rtp/rtcp port pairs (odd rtp port), blank lines in the session
description, wrong case of the format description, relative base URLs...

Change-Id: I502a04a7e1d690fd461b7ecf0b56c6a6c2ac1325
related-to-bug: 3452103