MediaSet: Do not remove sessions until they expire even if they are empty
MediaSet: Do not remove sessions until they expire even if they are empty

Change-Id: I07f5d9dca6e57073c28cea55c3b742fd0a5f9e4b

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