Adds a PREPARED state after baremetal node power on.

During a baremetal deployment there is a middle step which
is not currently represented. If the baremetal node powers on
but never connects to the deploy-helper, it is impossible to tell
from the database whether the deploy environment was not created
or whether the machine is dead.

Change-Id: I6be3d45fee28970cbb02945c518be34b2bc74689
Closes-Bug: #1184470
Merge "Adds a PREPARED state after baremetal node power on."