Add a -z flag to include zbot results in greps

[GLips]

This is worth discussion. It probably makes sense to include some zbot outputs, but not others—even with the -z flag.

[fimad]

I think we'd have to also update the history service to save zbot messages. I don't think they get logged anywhere right now.

That means we also have to opportunity to start tagging zbot output with which service it originated from. We could use that to filter which service output we cared about when grepping.