title: I get a error when using HoughCircles with Python OpenCV that a module is missing
body: <p>I have a small test code block trying to process a simple photo with a ball in it:</p>
  
  <pre><code>#!/usr/local/bin/python
  import cv2
  import numpy as np
  
  img = cv2.imread("b.jpg")
  gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
  circles = cv2.HoughCircles(gray,cv2.CV_HOUGH_GRADIENT)
  </code></pre>
  
  <p>When I try to run this I get:</p>
  
  <blockquote>
    <p>AttributeError: 'module' object has no attribute 'HOUGH_GRADIENT'</p>
  </blockquote>
  
  <p>I've been installing and reinstalling for two days trying to figure out whats wrong.
  Any help or pointers would be appreciated!</p>