extra/pylint.{sh,conf}: Cleanup: Move "ignored-classes" to config file

The ignored checkers/messages are specified in the config file, so the
ignored classes belong there too.
make check: Disable pylint checks on numpy members

It seems that pylint can't figure out some magic done by numpy 1.8.0,
so stbt.py would fail `make check` with:

    E1101:410,16:detect_motion: Module 'numpy' has no 'multiply' member
    E1101:411,20:detect_motion: Module 'numpy' has no 'ones' member
    E1101:411,50:detect_motion: Module 'numpy' has no 'uint8' member
    E1101:413,26:detect_motion: Module 'numpy' has no 'uint8' member
    E1101:1013,11:gst_to_opencv: Module 'numpy' has no 'ndarray' member
    E1101:1018,14:gst_to_opencv: Module 'numpy' has no 'uint8' member
    E1101:1096,9:_match_template: Module 'numpy' has no 'ones' member
    E1101:1096,59:_match_template: Module 'numpy' has no 'zeros' member
    E1101:1099,18:_match_template: Module 'numpy' has no 'float32' member
    E1101:1161,39:_match_template: Module 'numpy' has no 'uint8' member
    E1101:1277,22:_log_image: Module 'numpy' has no 'float32' member
    E1101:1988,24:_fake_frames_at_half_motion.FakeDisplay.frames: Module 'numpy' has no 'zeros' member
    E1101:1988,53:_fake_frames_at_half_motion.FakeDisplay.frames: Module 'numpy' has no 'uint8' member
    E1101:1989,24:_fake_frames_at_half_motion.FakeDisplay.frames: Module 'numpy' has no 'ones' member
    E1101:1989,52:_fake_frames_at_half_motion.FakeDisplay.frames: Module 'numpy' has no 'uint8' member

These are genuine numpy members (I tried them all in ipython).

Pylint 1.0.0 and 0.28.0 both fail to understand numpy 1.8.0. I didn't
have this problem with earlier versions of numpy (1.6.2, at least).