Pact dev checkpoint

Hey, all,

This is a checkpoint staging commit for core-hq related changes I made for the pact migration.
Note that pact-staging is tracking master right now, and pact-dev is where i was doing my work.

the things of main significance are new Elasticsearch API tools in the corehq/apps/api directory that are somewhat redundant with the existing caseapi

with the ES based apis, on pact fully ajax-based pagination and sorting works now, however with some caveats based upon form structure considerations (unlikely for generic reports though).

This also relies upon a pillowtop change to the case elastic index that needs to be reindexed for some of this functionality to work.

for pillowtop, a new case index using a property walker and establishing better date handling in the case object and all its properties