Open Stack

https://review.openstack.org/#/c/136490/

This is part of the infrastructure buildup for Cells v2 which is 
priority work in Kilo.  It is needed to get closer to a working cellsv2 
prototype.

This work is focused on methods for populating the instance_mapping 
table with data about current instances.  It is an important piece of 
the migration path to cells v2 so being able to continue working on it 
this cycle will help keep momentum on the cells v2 effort. Thanks.

-Andrew