Add non-stump based ocl Haar cascade classifier support.

For example, haarcascade_frontalface_alt2.xml is now supported.
Note that classifier's pattern of a cascade file must be consistent,
i.e., all trees must either have two nodes or one node, otherwise
unexpected results will occur.

Other fixes:
Test cases are updated.
Some unused codes are removed.
Fix some problems of haar when using OclCascadeClassifierBuf.

modules/ocl/include/opencv2/ocl/ocl.hpp

@@ -817,7 +817,7 @@ namespace cv
             OclCascadeClassifierBuf() :
                 m_flags(0), initialized(false), m_scaleFactor(0), buffers(NULL) {}
 
-            ~OclCascadeClassifierBuf() {}
+            ~OclCascadeClassifierBuf() { release(); }
 
             void detectMultiScale(oclMat &image, CV_OUT std::vector<cv::Rect>& faces,
                                   double scaleFactor = 1.1, int minNeighbors = 3, int flags = 0,