Avoid using cudaMemcpy for memcpy when there is no GPU and CUDA driver
Check the GPU mode to decide which memcpy to use
Switch to GPU mode when pointer is move to or from GPU in SyncedMemory
Implement @Yangqing's solution to copy memory in the SyncedMemory
Replace cudaMemcpy with caffe_gpu_memcpy in SyncedMemory per @longjon
Merge pull request #633 from kloudkl/cpu-only-memcpy

Support CPU only memcpy