Print log errors to STDOUT rather than discarding them

Previously, the default io-error-handler was log-generator/error, a
string constructor. This would cause exceptions raised during logging to
build a string, then discard it.

As a stop-gap to improve development experience, exceptions in logging
will now be written to STDOUT (captured during init!).
Merge pull request #10 from rkneufeld/aether-free-logging

Print log errors to STDOUT rather than discarding them