Change config file format to JSON

This changes the format of our config file from JS to JSON to comply with CFPB's front-end build conventions.

@ascott1 @mistergone @akiany @fna You'll need to copy `example-config.json` to `config.json` and add the API endpoints.

@fna I updated the Jenkins script per our email conversation. Can you merge this PR and see if anything explodes?

![selfie-0](http://i.imgur.com/qwPvJJc.gif)