Don't pass "args" into logging call

@gsakkis do you mind trying out this patch and see if this fixes #409 for you? I'm not entirely sure why this error is not caught by [this test](https://github.com/nvie/rq/blob/master/tests/test_worker.py#L118).

I also tried writing a new test but this doesn't catch the error either:
```python
def test_exception_handlers(self):
        """Ensure exception handling does not crash"""
        q = Queue()
        job = q.enqueue_call(div_by_zero)
        w = Worker([q])
        setup_loghandlers()
        w.handle_exception(job, *sys.exc_info())
```