Network elements modeling as objects

This patch, and eventually patch series, works towards having an
object oriented representation of the network primitives to ease
the handling, verification and extension of the vdsm networking
code.

The implementation is guided by the feature proposal:
    http://www.ovirt.org/Feature/NetworkReloaded

STATUS
=======
The implementation is very much in its infancy and a lot
is bound to change. Currently it is capable of creating and
deleting a bridged network over a nic or a bond. Also vlans
over what was mentioned before.

Have to implement:
- bridgeless network support.
- make netinfo have network entities, so the implicit setupNetwork
  info is automatic and does not clutter netmodels.py
- setSafeConfig, addNetwork and delNetwork.

Other stuff:
- Clean up the API. Currently it is hacky and lacks consistency.
- Try to implement the iproute2 configurator.

Change-Id: Ie6ded2ec4ab2f8ea9fdb83173cd8468caa92a2ae
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>