Set up a development environment

[rossbowen]

After git clone-ing the project:

• [x] A dev can buildout to install the Plone backend, for doing Plone development.
• [x] A dev can yarn start to run the Volto side, and use a docker container to spin up a basic Plone backend, for doing Volto development. Actually run Plone directly using plonectl.
• [x] Explain how to spin up in README.md.

A Plone backend can be spun up, with the Volto plugin applied, using:

docker run -p 8080:8080 -e SITE="Plone" -e ADDONS="plone.volto" plone/plone-backend:6.0.0a1 start

Further addons can be added using the ADDONS env variable, see run_plone.sh for an example.

[ajtucker]

• [x] Bootstrap local Plone development with buildout #12
• [ ] Add separate Dexterity based add-on for SPARQLWrapper and config #14

[cjfairchild]

@ajtucker to look at pipenv/buildout oddities when trying to build and run the plone-5 docker image.