Additional ipmi commands

This has two minor bug fixes discovered while doing this work -- security manager caching when it shouldn't, and a hard-coded exception handler duplicating the Sinatra exception handler.

It then implements a reset reboot operation for nodes that have IPMI credentials, including hard and soft reboots, and independent RBAC authorization for both.  (As well as restricting it by node, naturally.)

This makes it possible to actively use the IPMI support for, granted imperative, command and control of an aspect of the nodes.