Ma/org endpoint

Harden org creation endpoint for failure.

@opscode/server-team 
Not sure I totally understand; could you (Marc) expand?
We don't cascade delete because it's too slow to do that (at least last time we tested). Are you suggesting we adding a FK constraint preventing org deletion until we delete all the objects in the org? Or are you thinking we constrain on certain tables? Associations? That might be reasonable.