GPU docker support

    Try running tests for one submodule at a time if memory proves an issue.

### Using a Docker Image

For major releases we will create docker environments with everything pre-installed

For major releases we will create docker environments with everything pre-installed.

In order to get GPU support you will have to use the 

[nvidia-docker](https://github.com/NVIDIA/nvidia-docker) plugin.

``` bash

# This will the download the latest stable deepchem docker image into your images

docker pull deepchemio/deepchem

# This will create a container out of our latest image

docker run -i -t deepchemio/deepchem

# This will create a container out of our latest image with GPU support

nvidia_docker run -i -t deepchemio/deepchem

# You are now in a docker container whose python has deepchem installed

# For example you can run our tox21 benchmark