Fix JobManager remove method.

        """Cancel a job."""

        self.jobs[job_id].stop()

    def remove(self, job):

        return self.jobs.pop(job.id)

    def remove(self, job_id):

        return self.jobs.pop(job_id)

    def create(self, job_constructor, *args, **kwargs):

        """Create a new job and populate job id."""