Added Dockerfile to enable use of legacy packages etc.

[seabbs]

Hi,

I just wrote a quick Dockerfile to enable a colleague to assess this package for their workflow and thought adding to the package it might be helpful.

Based on the rocker/tidyverse container so all running instructions that are relevant there are required here.

Basic run command is:

docker build . -t rehr
docker run -d -p 8787:8787 -e USER=rehr -e PASSWORD=rehr --name rehr rehr

Thanks,

Sam