Fix HOLD state
Fix HOLD state

When responding to a build complete event, don't do anything to
the node if it is in the HOLD state.

Change-Id: I37e458198bfcd08472d07ca9c206c1b4551f3341

seandst/nodepool,citrix-openstack/nodepool,citrix-openstack/nodepool,seandst/nodepool,Tesora/tesora-nodepool,Tesora/tesora-nodepool