daily report generation no longer fails when filtering by both center and staff member
daily report generation no longer fails when filtering by both center and staff member

In this case the actual center list for the report may turn out to be
empty as we take an intersection of the selected center, and centers
corresponding to the selected staff member. Incorrect SQL is generated
if the client list for the report is empty; fix it.

svs/mostfit-private,Mostfit/mostfit,svs/mostfit-private,Mostfit/mostfit