MSRPChat: set from_uri attribute in __init__

darcs-hash:20090324074411-b2873-0eb23aefa90c220d7e0ff20abe555f34f27df913
MSRPChat: fix improper use of MSRPRelaySettings

darcs-hash:20090324074438-b2873-7c93cec7dc20d1928203a32ec3068abb22cb6085