don't define Service support if Twisted's service is not available
don't define Service support if Twisted's service is not available

inirudebwoy/AutobahnPython,RyanHope/AutobahnPython,dash-dash/AutobahnPython,dash-dash/AutobahnPython,markope/AutobahnPython,iffy/AutobahnPython,bencharb/AutobahnPython,iffy/AutobahnPython,meejah/AutobahnPython,Jenselme/AutobahnPython,crossbario/autobahn-python,oberstet/autobahn-python,oberstet/autobahn-python,ttimon7/AutobahnPython,tavendo/AutobahnPython,oberstet/autobahn-python,jvdm/AutobahnPython,iffy/AutobahnPython,hzruandd/AutobahnPython,Geoion/AutobahnPython,schoonc/AutobahnPython,nucular/AutobahnPython,dash-dash/AutobahnPython,crossbario/autobahn-python,crossbario/autobahn-python,dash-dash/AutobahnPython,iffy/AutobahnPython,tomwire/AutobahnPython