pilosa server console should be smarter and interactiver

[seebs]

Description

Console should be able to do things like "show current status" or "show stats", and possibly have a clean shutdown command other than ^C.

Success criteria (What criteria will consider this ticket closeable?)

Ability to run simple commands on console. I think as a starting point, I nominate info, status, and shutdown.

We might also want a bit more control over verbosity of logs -- the flood of updates about fragment writes would make the console hard to use.