[PASS] InjectDoubleBuffer (#405)

include/tvm/ir.h

include/tvm/ir_pass.h

include/tvm/schedule.h

python/tvm/build_module.py

python/tvm/ir_builder.py

python/tvm/schedule.py

src/api/api_lang.cc

src/api/api_pass.cc

src/pass/inject_double_buffer.cc

src/pass/storage_access.cc

src/pass/storage_access.h

src/pass/storage_flatten.cc

src/pass/storage_sync.cc

src/schedule/schedule_lang.cc

src/schedule/schedule_ops.cc

tests/python/integration/test_gemm.py

tests/python/unittest/test_pass_inject_double_buffer.py

topi/recipe/gemm/cuda_gemm_square.py