Add API uuid <-> id mapping

On the API side, when creating a new node or port, translate 'chassis_id'
and 'node_id' from uuid to id, internally id will be always used to do
database operations. The opposite will happen when returning data back
to the user the internal id will be translated to an uuid.

Change-Id: I84782268c4317b4eec53fdcdfc6cb2b901b22780
Merge "Add API uuid <-> id mapping"