Figure out log file support

[astrobokonon]

It's probably a good idea to have flat log files as backup for Mr. Freeze, and ideally per-instrument like we've been doing for a while now.

Off the top of my head, it seems like this should be done using the log file manager and appropriate log levels. But, I don't know how to do that.

Seems like I should do a scan of the configuration file, and set up a log output file per instrument that I find? Once that's done I could probably define a series of log objects that get rotated, etc., but there are many details to figure out still.

This is probably something that will get folded back up the chain to ligmos/DataServants, but it's needed here first.