del proper service object when removing MediaRenderer device client
del proper service object when removing MediaRenderer device client

opendreambox/python-coherence,furbrain/Coherence,coherence-project/Coherence,opendreambox/python-coherence,sreichholf/python-coherence,ismaelgaudioso/Coherence,ismaelgaudioso/Coherence,sreichholf/python-coherence,unintended/Cohen,furbrain/Coherence,unintended/Cohen,coherence-project/Coherence