add models.py for valid app structure
add models.py for valid app structure

qedsoftware/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,puttarajubr/commcare-hq,puttarajubr/commcare-hq,puttarajubr/commcare-hq,puttarajubr/commcare-hq,qedsoftware/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq,qedsoftware/commcare-hq,dimagi/commcare-hq