Lazy-loading the main part of the app (#197)

* Splitting main part of app out of the main bundle.

Also improving the transition from intro to compressor.

* Showing error if app fails to load.

* lol these aren't async

* Please don't tell anyone I did this

* Spinner if user selects a file before the app has loaded. (#208)

src/components/App/custom-els/FileDrop/index.ts

@@ -1,4 +1,4 @@
-import { bind } from '../../../../lib/util';
+import { bind } from '../../../../lib/initial-util';
 import './styles.css';
 
 // tslint:disable-next-line:max-line-length