Add v2 API support for the Cisco plugin

Add v2 API support for the Cisco plugin
Blueprint cisco-plugin-v2-api-support

New meta-plugin which makes use of the Quantum db_plugin and supports
the new v2 API
Changes to the Cisco DB model, now reusing quantum DB for core attributes
Changes to the device sub plugins to access the quantum DB for core
resources' state versus Cisco DB
Addition of fake/dummy drivers to support testing of the device sub
plugins even without actual hardware
New v2 unit tests which exercise the meta-plugin and the device sub
-plugins as well
In general creating new v2 modules such that v1.x code can be deprecated
easily by deleting the older modules. The following files are v2
versions of older modules, only the imports have changed, most of the
other code is the same as from the older modules (already reviewed):
quantum/plugins/cisco/common/cisco_credentials_v2.py
quantum/plugins/cisco/db/network_db_v2.py
quantum/plugins/cisco/db/network_models_v2.py
quantum/plugins/cisco/db/nexus_db_v2.py
quantum/plugins/cisco/db/nexus_models_v2.py
quantum/plugins/cisco/db/ucs_db_v2.py
quantum/plugins/cisco/db/ucs_models_v2.py
quantum/plugins/cisco/nexus/cisco_nexus_plugin_v2.py
quantum/plugins/cisco/ucs/cisco_ucs_inventory_v2.py
quantum/plugins/cisco/ucs/cisco_ucs_plugin_v2.py
quantum/plugins/cisco/segmentation/l2network_vlan_mgr_v2.py

All changes are contained with the Cisco plugin.

(Sumit & Rohit)

Change-Id: Ib82a9f843548c286c84ba63caf5406a773ac85b1