Since `log(message)` is part of the `Multiple` or `Base` class that comes with Resque, this has to be compatible.

I initially just deferred to `super`, e.g. `super(format_message(message,args,exception))` however that caused tests to fail, because the base class calls `log` on its `@worker` and for some of the tests, `@worker` is nil, and Resque doesn't check for it.  So either Resque has a bug, or the test doesn't sufficiently simulate the real world, but that didn't feel like a problem I should be solving in this PR.