Catalog driver generates v3 catalog from v2 catalog

The default get_v3_catalog method in the catalog driver would just
raise NotImplemented. This method is given a default implementation
that generates the v3 catalog by translating the v2 catalog.

With this change, the templated and kvs catalog backends can
generate a v3 catalog.

Closes-Bug: #1313458
Change-Id: I1646c7dcab90f2e0e9e370f48f7ee3643bd2fe3d
Merge "Catalog driver generates v3 catalog from v2 catalog"