Checkpoint GPU scheduling API changes and test updates.
Merge branch 'master' into test_gpu
Legacy cuda* calls are needed on ScheduleHandle as well.
Merge branch 'master' into test_gpu
Convert tests and apps to using gpu_ names.
Merge branch 'master' into test_gpu
Merge branch 'master' into test_gpu
Merge branch 'master' into test_gpu

Conflicts:
	test/correctness/hello_gpu.cpp
Merge branch 'master' into test_gpu
Merge branch 'master' into test_gpu

Conflicts:
	apps/bilateral_grid/bilateral_grid.cpp
	apps/interpolate/interpolate.cpp
	apps/local_laplacian/local_laplacian.cpp
Merge branch 'master' into test_gpu
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Added new files to CMake build
Modified reorder implementation to avoid VarOrRVar::operator =
Added some more nacl demos as an app
nacl demo tweaks
Added a second reaction-diffusion demo