Inventory model to support network devices

[Sulochan Acharya]

As per the discussion in the community meeting, we would like to have better inventory models to accommodate driving/deploying Openstack service like Ceph, Swift, Cinder etc. The current modeling might not be suitable to do this. The key point is to support network devices, we currently dont have explicit support to do network device modeling.

some thoughts from group here:
https://docs.google.com/document/d/1N3f_H3bjZ1a08wkxRLCMt5ANXRGmFAOEUZ_mtI3BYxw/edit?usp=sharing

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/361175

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/361175
Committed: https://git.openstack.org/cgit/openstack/craton/commit/?id=900ac323afb604ff76484a353f15255e4adc6f72
Submitter: Jenkins
Branch: master

commit 900ac323afb604ff76484a353f15255e4adc6f72
Author: Sulochan Acharya <email address hidden>
Date: Fri Aug 26 14:21:40 2016 +0100

    Adds model for network devices

    - Adds db model to represent a network.
    - Adds db model to represent a network interface.
    - Adds db model to represent a network device.

    - Net device should follow the same partent child
    pattern that any other devices do.

    - Other devices should be able to point to a network device
    as its parent device.

    - Net devices which combination with other net devices
    and hosts gives us the ability to represent a cab. A cab
    is the group of hosts that all connect to the same Top of
    the Rack Switch.

    Closes Bug: 1606872
    Implements: blueprint craton-inventory-network-device-support

    Change-Id: Id5f2f44bcd2b87ce61bf8a6d1f1114079d5637a6