IPMI Plugin

Cleaning up some code regarding how the hosts are stored in the ipmi
component. Replaced earlier ad-hoc linked list with opal_list
IPMI Plugin - Cleanup - Removing some commented code
Adjusting whitespace and indentation
IPMI plugin - Added a call to destroy the opal list during finalize stage.
IPMI PLugin - change return codes for func to find existing nodes
Merge branch 'vin_ipmi_list'