Fixed bug in RTPTransport when using both ICE+STUN and SRTP

darcs-hash:20090220174347-58103-699ccdb5a4d843930d5074ef0b70171e3f5aa1e8
Implement waiting for RTPTransport to initialize in Session

darcs-hash:20090220174438-58103-4a6fd66b12d90c07c228dc07d880c38d17b8ebc0