Nvidia 18.04 support

[tfoote]

This is changing the nvidia snippet to be conditioned on 16.04 vs 18.04.
Following behaviors from:

• https://gitlab.com/nvidia/opengl/blob/ubuntu16.04/glvnd/runtime/Dockerfile
  vs
• https://gitlab.com/nvidia/opengl/blob/ubuntu18.04/glvnd/runtime/Dockerfile

Currently it's conditioned on the host OS, however because the snippet is done in the image I think it would be better to have it conditioned on the image's OS.

I'd originally thought that it was coupled to the host OS as you need the same nvidia drivers as the host. And it worked for 16.04 host and an 18.04 image using the 16.04 injection. However when using the 18.04 host it broke in #14.

@ruffsl can you verify that this works for you? And we can figure out how the parameterization should be done?

[ruffsl]

I had to update my python docker module in the env environment, but other than that it seems to be working. I can't seem to kill/exit with crtl+c though.

[tfoote]

@ruffsl I rebased this on top of #24 could you validate it works for you on 18.04?

[ruffsl]

Awsome, its working rather slick with rviz2 on my nvidia laptop. However, do we still need the FROM nvidia to COPY the 10_nvidia.json if its >= 18.04? Kind of a bummer I wait to download ~2.47GB on my home network for 107 bytes of json. @flx42 does this file change often? Is there tracked URL we should fetch it?
Perhaps https://gitlab.com/nvidia/opengl/raw/ubuntu<distro# e.g. 18.04>/glvnd/runtime/10_nvidia.json?inline=false

# Preamble from extension [nvidia]
# Ubuntu 16.04 with nvidia-docker2 beta opengl support
FROM nvidia/opengl:1.0-glvnd-devel-ubuntu18.04 as glvnd

FROM osrf/ros:crystal-desktop
# Snippet from extension [nvidia]
RUN apt-get update && apt-get install -y --no-install-recommends \
    libglvnd0\
	libgl1 \
	libglx0 \
	libegl1 \
	libgles2 \
    && rm -rf /var/lib/apt/lists/*
COPY --from=glvnd /usr/share/glvnd/egl_vendor.d/10_nvidia.json /usr/share/glvnd/egl_vendor.d/10_nvidia.json

ENV NVIDIA_VISIBLE_DEVICES ${NVIDIA_VISIBLE_DEVICES:-all}
ENV NVIDIA_DRIVER_CAPABILITIES ${NVIDIA_DRIVER_CAPABILITIES:+$NVIDIA_DRIVER_CAPABILITIES,}graphics