Support sudo

[GiselleSerate]

Currently we only support SSHing as root; perhaps it would be helpful to support SSHing as somebody who isn't root, but has sudo. This will affect every command we run on the target system. Caveat, sometimes scripting and sudo doesn't play nice together, so this won't necessarily be the most straightforward thing. Possibly #60 could be fixed by using sudo instead of sshing as root, but I don't know enough to assert that for sure. That's the only reason I'd think this issue important; otherwise it is easy enough to enable root SSH from a sudoer account (as documented in our Setup Instructions).