Add Dockerfile and notes to README

[dnephin]

Hello,

This PR adds a Dockerfile to support building a distribution without having to manually install all of the dependencies on the host.

[dnephin]

@fehguy Any reason you're closing this without any comment?

Do you need a rebase?

[dnephin]

Copying and pasting a file in is not at all a manual merge.

I can rebase or change this PR if necessary.

[fehguy]

Sorry! I manually merged it into develop_2.0

[dnephin]

@fehguy copying my work and committing it as yourself is not a "manual merge".

You also missed the .dockerignore which is important. If you'd like me to remove the README documentation and re-submit to the develop_2.0 branch, I can do that.

[fehguy]

hmm intention wasn't to copy, this made it easier to merge to the correct branch. I can undo and accept your PR if you like.

[dnephin]

I can submit the PR to develop_2.0