Reduce the verbosity of the "Aphlict" log

Summary:
See PHI1692. Currently, the Aphlict log is ridiculously verbose. As an initial pass at improving this:

• When starting in "debug" mode, pass "--debug=1" to Node.
• In Node, separate logging into "log" (lower-volume, more-important messages) and "trace" (higher-volume, less-important messages).
• Only print "trace" messages in "debug" mode.

Test Plan: Ran Aphlict in debug and non-debug modes. Behavior unchanged in debug mode, but log has more sensible verbosity in non-debug mode.

Differential Revision: https://secure.phabricator.com/D21115