json schema and json-edit

Great to see progress on this. I think it will be a very valuable. I'll attempt to write out some of the thoughts that I had in my head for #1. I wondered if we could leverage JSON schema for validation/meta and then build/use something like [json-editor](https://github.com/jdorn/json-editor) or [alpaca](https://github.com/gitana/alpaca) to quickly create a usable form. I did some tests a while ago auto-building a JSON schema from a R `list`, so you could have a

sample input `list` -> create a JSON schema -> could be supplemented or customized by advanced users -> create a form that could be used with or without Shiny

I might be way off, but since you seemed very open to input, I thought I would share my very preliminary thoughts.

I had a list of some applicable JavaScript in https://github.com/timelyportfolio/buildingwidgets/issues/35.

No project files or tests are named. Start by reviewing this proposal, referenced issue #1, and buildingwidgets issue #35, then compare the json-editor and Alpaca approaches; done would require an agreed, concrete scope for JSON Schema validation and form generation with or without Shiny.

Written by the indexing model from the issue text.