Update couchexport/tasks.py
Update couchexport/tasks.py

adding assert for settings.CACHES - else get_cache on a nonexistent ID fails hard
qedsoftware/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq