Merge pull request #633 from dimagi/cz

reenable global site_code uniqueness
clean imports
add const for static case types, update references, more import cleanup
delete generic tests.py
add const for the index reference between supply points and products
super simple tests for making supply points and products
Merge pull request #635 from dimagi/cz-commtrack

very minor code cleanup and basic tests for making objects
fix notify_exception arguments, remove imports