Make port creation API idempotent regardless of HTTP method
Allow MAC to network ID association to be overwritten via API
Ensure port is greater than 0 when updating a port
Added check to start-up database sync to ensure ports are registered to existing networks
   - Work-around for q-dhcp bug that leaves remnant ports of deleted subnets

Conflicts:

	ryu/app/rest.py

Conflicts:

	ryu/app/rest.py
Make port creation API idempotent regardless of HTTP method
Allow MAC to network ID association to be overwritten via API
Ensure port is greater than 0 when updating a port
Added check to start-up database sync to ensure ports are registered to existing networks
   - Work-around for q-dhcp bug that leaves remnant ports of deleted subnets

Conflicts:

	ryu/app/rest.py

Conflicts:

	ryu/app/rest.py