Adds test for Floating Ips bulk Nova V2 API

This patch adds the test for following Nova V2 APIs-
- Create Floating Ips bulk
- Delete Floating Ips bulk
- List Floating Ips bulk

This patch also adds the config option for unallocated
Floating IP Range

Change-Id: I6af52bb2ce2caadf8491740097df71d041643e78
Merge "Adds test for Floating Ips bulk Nova V2 API"