fix missing variable definition - thx netmask for spotting this
fix missing variable definition - thx netmask for spotting this

closes #137

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