kmssdpcontext: create media copy when it is added to msg
kmssdpcontext: create media copy when it is added to msg

Change-Id: I094e764089fca2b9f317f5a6dbbd2490b02f4667

TribeMedia/kms-core,ESTOS/kms-core,ESTOS/kms-core,shelsonjava/kms-core,shelsonjava/kms-core,Kurento/kms-core,Kurento/kms-core,Kurento/kms-core,TribeMedia/kms-core,ESTOS/kms-core,ESTOS/kms-core,Kurento/kms-core,TribeMedia/kms-core,shelsonjava/kms-core,shelsonjava/kms-core,TribeMedia/kms-core