add feature flag for session meta API
add feature flag for session meta API

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