This changeset adds a new parameter, 'allocation_pools' to the 'subnet'
resource of the Quantum v2 API.
Allows for creating and validation of subnets with multiple allocation pools.
This commit only deals with POST verb (subnet creation).
PUT verb (subnet update) will be dealt with in a subsequent commit.
This is the first commit for fixing bug #1016308
Change-Id: Ic356dcb5dcfa46af8ecc7e598529881f8bcbbeed
17bed81d11