add a development / test application

[alicewriteswrongs]

It would be nice to have a basic web application in this repo that could run the code for testing purposes. I think having that would require more of the search code to be in this repo though, specifically:

• query generation code
• facet code

and possibly other things. the query generation and facet code possibly already should be, since we share those things between Open and OCW right now.

[alicewriteswrongs]

this could be just a simple create-react-app application.