* remove some of the react errors, start to fix webpack HMR errors
* start upgrade to webpack 4
* more stuff to update webpack
* update webpack configs to work with webpack 4
* remove linting from truncate script
* for #950, upgrade babel to v7
* fix linting errors
* for #950, remove @babel/core from devDependencies (so it's only in dependencies) and change babel-loader config to use .babelrc
* for #950, changes to .babelrc to make work
* for #950, include core-js modules in webpack config for IE support with babel/plugin-syntax-dynamic-import
* for #950, update babel and associated packages to LTS
* delete unused files, move webpack configs to their own directory
* start of improved developer documentation, moving everything to developer_docs/ directory
* documentation updates
* Fixes#497 by adding support for an optional new env variable, S3_BUCKET_URL_BASE
* Add a section to README about optional S3 bucket URL base configuration.
