add two samples
remove the images in ocl sample folder
add results verification to facedetect and hog samples
Fix a bug when pushing pointers of arguments into std::vector.
When argument pointers pushed into an vector and the pointers point to
address on stack, we need to make sure they are valid until kernels are
successfully flushed onto the queue.
revise perf
Fix 2.4 ocl Canny.
This fix is a workaround for current 2.4 branch without introducing an
additional oclMat buffer into CannyBuf object.
Test case is cleaned up.
Volatile keywords in kernels are removed for performance concern.
adjust test cases
fixed some gpu tests (different rounding results due to float arithmetics)
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.
Fix brute_force_matcher's hung on some Intel CPU OCL
Merge pull request #930 from pengx17:2.4_haar_ext
Merge pull request #927 from bitwangyaoyao:2.4_perf
Merge pull request #925 from pengx17:2.4_canny_tmp_fix
Merge pull request #924 from pengx17:2.4_arithm_fix
Merge pull request #918 from bitwangyaoyao:2.4_samples
Merge pull request #932 from bitwangyaoyao:2.4_fixBFM
Merge pull request #931 from jet47:gpu-test-fixes