This adds an extension that provides a REST API for the bulk creation,
deletion and listing of floating IPs. The interface is accessed via
/v2/{tenant_id}/os-floating-ips-bulk
This forms part of the work to provide APIs for functionality currently
implemented by nova-manage that needs direct db access so nova-manage
can eventually be removed
Implements: blueprint apis-for-nova-manage
DocImpact
Change-Id: I621e2b070a896f7230cdf3f26f78ded85e72cf16