Integration of tegra and cuda

General clean-up, bug fixes, and re-factoring of directory structure; and documentation improvements.

The yolo service now has versions for the virtual architectures of cuda for AMD64/nVidia and tegra for ARMv8/nVidia; these are equivalent to Intel/LINUX w/ PCI GPU card and nVidia Jetson family, e.g. Nano and TX2. The service label remains yolo across all versions; specialization may be performed by indicating the url for the service.