Pass positional arguments to cover environment.
Eliminate an import loop

Turns out handlers.py imports middleware.py, which causes an import
loop when nose imports test_middleware.py all by itself.  Eliminate
the import loop by using wrap_log_handler() instead of
BarkMiddleware.__call__().  (This is less than ideal, but the log
record fields we're trying to fill don't really make sense anyway.)
Construct a basic function test for bark.