#30: cleanup react, keep only basic stuff

* based upon https://leanpub.com/setting-up-es6/read#sec_webpack-babel

webapp/.gitignore

@@ -9,16 +9,6 @@
 # production
 /build
 
-# misc
-.DS_Store
-.env.local
-.env.development.local
-.env.test.local
-.env.production.local
-
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
-
-# css files (we're using sass, css is always auto generated)
-src/**/*.css

webapp/config/paths.js

@@ -47,7 +47,6 @@ module.exports = {
   appIndexJs: resolveApp('src/index.js'),
   appPackageJson: resolveApp('package.json'),
   appSrc: resolveApp('src'),
-  yarnLockFile: resolveApp('yarn.lock'),
   testsSetup: resolveApp('src/setupTests.js'),
   appNodeModules: resolveApp('node_modules'),
   publicUrl: getPublicUrl(resolveApp('package.json')),

webapp/config/polyfills.js

@@ -1,22 +1,5 @@
 'use strict';
 
-if (typeof Promise === 'undefined') {
-  // Rejection tracking prevents a common issue where React gets into an
-  // inconsistent state due to an error, but it gets swallowed by a Promise,
-  // and the user has no idea what causes React's erratic future behavior.
-  require('promise/lib/rejection-tracking').enable();
-  window.Promise = require('promise/lib/es6-extensions.js');
-}
-
 // fetch() polyfill for making API calls.
 require('whatwg-fetch');
 
-// Object.assign() is commonly used with React.
-// It will use the native implementation if it's present and isn't buggy.
-Object.assign = require('object-assign');
-
-// In tests, polyfill requestAnimationFrame since jsdom doesn't provide it yet.
-// We don't polyfill it in the browser--this is user's responsibility.
-if (process.env.NODE_ENV === 'test') {
-  require('raf').polyfill(global);
-}