[JIRA] (BIT-1185) topic/dnthayer/broctld-work

Just doing a hash of broctl.cfg itself wouldn't work very well, because there are various ways that the
broctl config can change:

I don't think I'm too concerned about these, as generally they all
seem rare enough that an additional warning wouldn't hurt much.

I have another idea though: could we pickle the relevant Python data
structures (i.e., config and nodes) and hash the binary representation
coming out of that?