Wire up node power state update logic via IPMI

This adds a simple logic wrapper that handles errors and updates power state
in a central fashion to the node object.  This is also the entry point that we
can use to trigger background processing by sending that message,
asynchronously, to the node instance.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Implement the TorqueBox scheduled job class to trigger power polling

This implements the logic behind monitoring power state for nodes: trigger a
regular update in the background for any eligible node.  We implement the Ruby
class that TorqueBox triggers from the scheduled job poller here.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Deploy the scheduled IPMI job into TorqueBox

This wires up the task scheduler and the IPMI power state update job to work
together, so that we kick off a power state check every five minutes.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>