fixed ocl tests for BlendLinear, BoxFilter, Integral
fixed test for CvtColor RGB -> Luv
fixed ocl_integral
Fix epsilon for OpenCL function ConverTo, for convertation from float to integer types
Fix error in OpenCl version of meanstddev for continues src and not continues mask
Merge pull request #3035 from ElenaGvozdeva:ocl_test_fix
Merge pull request #3043 from vbystricky:ocl_ConvertToAccurTestFix
Merge pull request #3045 from vbystricky:ocl_MeanStdDevFix