CXX-265 Configure logging through startup options

A few comments/questions:

-For cleanup of appenders, there's a clearAppenders() function, and this will actually delete the appenders.  Though it seems clear that when you attach the appender you hand ownership of it over to the log domain, users using these options won't see that call, and I wonder if they'd be surprised by this behavior.  Also, since we're not using the appender handles at all, or allowing the user to use them, I wasn't sure how important it was to call clearAppenders() at all.

-Where should configureLoggingOptions() live?  Options.cpp seems like an ok option, but I think there's probably a better fit.  If I add a cleanup function that should probably live in the same place.

-Should there be a way to configure, through options, specific minimum logged severity levels for different logging domains?  If you were doing it manually, you'd be able to set it by component.
If 'verify' is defined here it is an error, I think, because it means that it has leaked out of dbclient.h? Or perhaps pulling in log.h is making it 'real 'again? In any event, your use of it below suggests to me that this is more of an integration test.