added GPU non local means brute force filter + tests

fixed MCVC warnings

update gpu tests

added convert functions to BruteForceMatcher_GPU
other minor fixes

fixed BFM warning ("cannot tell what pointer points to")

*fixed some warnings
*finished gpu test port to gtest framework

minor fixes and refactoring of GPU module

added assertion after all kernels calls

added test for SURF_GPU and reprojectImageTo3D

2) NVidia tests for GPU
3) FD sample that uses NVidia's interface.