Objects and models file structure inconsistency

[Andriy Popovych]

Objects in Fuel are wrappers for SQlAlchemy models which provide CRUD interface for them.
Currently there are many inconsistencies between this entities in file structure. For example:

1. We have NodeGroup, Node, NodeNICInterface, NodeBondInterface in models/node.py but in objects structure
they represents in objects/node_group.py, objects/node.py, objects/interface.py, objects/bond.py. In such case models in models/node.py can split in separate files.
2. NodeNICInterface and NodeBondInterface can be renamed NICInterface( or Interface) or BondInterface (or Bond). They have many-to-one relation with node and it can be shown only through foreign key not name.
3. IPAddr and IPAddrRange from models/network.py can be split due to structure in /objects dir, models/network.py renamed into network_group.py.