sdp_utils (sdp_message_create_from_src): add attrs from source SDP
sdp_utils (sdp_message_create_from_src): add attrs from source SDP

Change-Id: Idbfef972e0ed0b457497160bbcfafd3b10b1f2fb

Kurento/kms-core,TribeMedia/kms-core,TribeMedia/kms-core,ESTOS/kms-core,KurentoLegacy/gst-kurento-plugins,TribeMedia/kms-core,Kurento/kms-core,ESTOS/kms-core,Kurento/kms-core,ESTOS/kms-core,shelsonjava/kms-core,ESTOS/kms-core,KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins,Kurento/kms-core,shelsonjava/kms-core,shelsonjava/kms-core,shelsonjava/kms-core,TribeMedia/kms-core,KurentoLegacy/gst-kurento-plugins