Rewrite distanceToCenters.
It supports NORM_L1 distance types now and can
use user provided indices.
Also fixed a bug of kmeans where distance pointers should be float instead
 of double.

NORM_L2 changed to NORM_L2SQR, Accuracy and Perf tests are added

added ROI support in accuracy test of distanceToCenters
fixing typo
Merge pull request #1696 from apavlenko:fix_typo_GpuMaterials
Merge pull request #1657 from KonstantinMatskevich:ocldistanceToCenters
fixed ocl::flip