Add FixedIP Object implementation

This adds the FixedIP object implementation to allow nova-network
to perform these operations with an object.

Related to nova-network-objects

Change-Id: I262b316e3c509f3a5ea6629e74b62011c7d35ba4
Add FloatingIP object implementation

This adds a FloatingIP object for use by nova-network.

Related to blueprint nova-network-objects

Change-Id: I22832c7d22af2fbd45bac790286ad2f4ce2e1fd6
Merge "Add FixedIP Object implementation"
Merge "Add FloatingIP object implementation"