Paver: fail if pylint/pep8 violations threshold is breached.

& like
```
R0801(duplicate-code):  1,0: Similar lines in 2 files
==courseware.management.commands.regrade_partial:51
==courseware.management.commands.remove_input_state:112
        module_state = module.state
        if module_state is None:
            # not likely, since we filter on it.  But in general...
            LOG.info("No state found for {type} module {id} for student {student} in course {course_id}"
                     .format(type=module.module_type, id=module.module_state_key,
                             student=module.student.username, course_id=module.course_id))
            return

        state_dict = json.loads(module_state)
```