properly handle empty dates defined in the xml in commtrack blocks
properly handle empty dates defined in the xml in commtrack blocks

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