Make sure role_requires table is created before we start importing barclamps.
Update node_role and node models to make adding implicit barclamps work.
Make node_role.name vaguely useful for debugging.
Merge pull request #600 from VictorLowther/pull-req-master-6b623130e3c620b214baad504771b72ddf86cbb8

Fix up role_requires logic to make automatically adding implicit roles actually work. [1/1]