statedetect: pylint and dependencies fixes

- Corrected the depency for opencv bindings. Even though the library is
  imported as "cv2", the package containing it is called
  "opencv-python".
- pylint: ignore no-member warnings; cv2 pulls it's memebers dynamically
  from the underlying libopencv, so pylint can't see them.

setup.py

@@ -80,7 +80,7 @@ params = dict(
     ],
     extras_require={
         'other': ['jinja2', 'pandas>=0.13.1'],
-        'statedetect': ['numpy', 'imutils', 'cv2'],
+        'statedetect': ['numpy', 'imutils', 'opencv-python'],
         'test': ['nose'],
         'mongodb': ['pymongo'],
         'notify': ['notify2'],