Refactoring to remove the instance permission check.  All permission definitions should assume an expression style permission check.
Fix some python2 thingamajiggers. [ci skip]
Finish refactoring the rules, and get rid of the separate django/sqlalchemy concerns.  It never worked anyway.
Cleanup and repairs for testing.
Fix issue where inheritance checking dictionary forgot about the key entries not related to inheritance.
More fixes and cleanup
Python2 fixes.
Try to discern what the session is without expecting the user to pass it.
Fix issue where generic deferred rules were not being invoked with individual rule requests.
Tweak inheritable dict to search and use the rule applying to the most derived superclass.  Additionally, disallow multiple position checks in the inheritable dict.  TODO: Figure out how to allow bearer inheritance checking.
Manually specify a join condition to ensure that joins work correctly
Have shield return uniform types.
Merge pull request #2 from concordusapps/refactor

Rework shield to remove the @rule.expression decorator.