Add a Dockerfile and fig.yml

Signed-off-by: Daniel Nephin <dnephin@gmail.com>
Add docs about using docker and fig.

Signed-off-by: Daniel Nephin <dnephin@gmail.com>
Merge pull request #215 from dnephin/add_dockerfiles

A Dockerfile and fig.yml
Merge branch 'master' of github.com:FarmBot/OpenFarm