Implements regions resource in 3.2 Catalog API

Adds CRUD implementation in SQL and KVS catalog drivers
for hierarchical regions support. The SQL driver implements
the region hierarchy using a simple adjacency list model
since it is expected that typical deployments will only
have a handful of regions, and the current regions API does
not offer any complex hierarchy querying that would make
a nested set model more appropriate.

Implements: blueprint first-class-regions

Change-Id: I2d4cca19008b92ef5758181b1792726834db7f7a
Merge "Implements regions resource in 3.2 Catalog API"