don't do any extra filtering if using a case footprint

fixes http://manage.dimagi.com/default.asp?104213

basically the previous footprint behavior was misleading and designed specifically to support parent-child case references in a single form. so when you said `footprint=True` you got all the filtered child cases, and then the footprint (the parents) got added.

however for the commtrack workflow you want the supply point cases, but those are only "owned" by an index reference from the user-location-mapping case, so the initial filter removes that and then the footprint doesn't go find them.

the right behavior (which is what the phone would do) is to just provide the whole casedb, including the footprint, and then let the additional filtering happen in touchforms (which it already does).

this might make certain touchforms usage slower (apps leveraging multiple case types and parent/child case references) but can revisit that if it becomes an issue.