add foreign key to presentation
add foreign key to presentation
pyconca/2013-web,toulibre/symposion,pinax/symposion,euroscipy/symposion,pyohio/symposion,pydata/symposion,pyconca/2013-web,TheOpenBastion/symposion,faulteh/symposion,pydata/symposion,mbrochh/symposion,python-spain/symposion,TheOpenBastion/symposion,NelleV/pyconfr-test,pyconau2017/symposion,pyohio/symposion,miurahr/symposion,mbrochh/symposion,euroscipy/symposion,faulteh/symposion,pyconau2017/symposion,python-spain/symposion,NelleV/pyconfr-test,toulibre/symposion,pinax/symposion,miurahr/symposion