Add a new extension called 'contrail' for extended attributes such as fq_name that contrail adds to other resources.
Also needs changes to provisioning script to add this new extension to the config file.

Change-Id: I54778963f2710b17c6202b15ea1471872be4db53
Closes-Bug: 1355384
Merge "Add a new extension called 'contrail' for extended attributes such as fq_name that contrail adds to other resources. Also needs changes to provisioning script to add this new extension to the config file."