Run external commands with elevated permissions

[hyperthunk]

Extends (possible) #74 - the way I currently see this working, is that you've got another (stand-alone) systest node that was launched with elevated permissions. You forward the request/config to that node, and it executes the command(s) on your behalf.

One use-case for this would be running pf or iptables to sever network connectivity during test runs.