blueprint api-operational-status

blueprint api-operational-status

Adds a new attribute expressing current operational status for port and network resources

Also includes:
- db models: changes to accomodate operational status concept
- unit tests: changes to include different validation functions for API v1.0 and v.1.1

This changeset does not include changes to the client library

NOTE: Addressing issue concerning unit tests for OVS plugin. API unit tests launched with
PLUGIN_DIR set to Cisco's plugin work fine as well.

Change-Id: I0c4f0f8a8c392bae75c668c28070364ca230f965