Require a target name when instantiating a node

This is effectively a required db field; without it, the watermark
calculation can be wrong until it's filled in, so make sure it's
there to start.

Also some minor logging changes.

Change-Id: Idc5a9cd40fe330f7a1aea4a5513267ee3c254f60
Make the target name required in the schema

Change-Id: Icccdc1cc545391fa17544f555bc0537540a53bd8