add ability to populate case db cache with an initial list
add ability to populate case db cache with an initial list

also add doc string to populate

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