Add a custom iboot power driver for nova bm.

Adds a custom power driver for nova baremetal so that
iBoot capable devices can be used.

In order to support multiple baremetal nodes attached to a single PDU
you can specify a pm_address in the format of address:port,relay.
If only an address is specified port and relay use defaults.

Tested locally with an iBoot G2.

Fixes bug 1226042
Implements nova-barmetal-iboot-g2-driver

Change-Id: I155f364f4ff6d77b34ded46de60c5cbca26596a2
Merge "Add a custom iboot power driver for nova bm."