Add ocl implementation of the sepFilter2D into img_proc module.
Fix compilation warnings
this commit prevents segfaults in case of opencl disabled
Change sprintf to cv::format, and EXPECT_MAT_NEAR to OCL_EXPECT_MATS_NEAR
Change threshold from 2.0 to 1.0 in the test
Merge pull request #2077 from ilya-lavrenov:tapi_context
Merge pull request #2055 from vbystricky:ocl_sepFilter2D