MediaSinkImpl: Fix linking problem with filters
MediaSinkImpl: Fix linking problem with filters

Update to gstreamer version 1.2.4 has raised a possible race condition
and caps apparently do not share a common format when they do, removing
checks makes link work (because we already know that are compatible)
and make it faster also

Change-Id: I74abcd97a113d7015dc1d2d3276d374bfc72963c

shelsonjava/kurento-media-server,Kurento/kurento-media-server,Kurento/kurento-media-server,lulufei/kurento-media-server,TribeMedia/kurento-media-server,shelsonjava/kurento-media-server,mparis/kurento-media-server,todotobe1/kurento-media-server,todotobe1/kurento-media-server,lulufei/kurento-media-server,mparis/kurento-media-server,TribeMedia/kurento-media-server