Networking workflow now handles no-router case

The change introduced in Ib93207505872c7a0cc49dd33ed01239ad114cac3
makes the get-default-router-id command to assign "NOT_FOUND" if there
is no router in the current tenant.  Now the workflow will properly
handle this case and will properly halt.  Also, the router get reset
to None afterwards, so subsequent deployments will succeed if the
router is added.

Requires Ib93207505872c7a0cc49dd33ed01239ad114cac3 to be merged

Change-Id: I78e2f3ae86c54628dd69641caebcc5ed1980835d
Partial-Bug: #1261356
Merge "Networking workflow now handles no-router case" into release-0.4