ES6 module format conversion

[wkeese]

Convert code to use Webpack as a pre-cursor to converting code to run on lit-html while still being able to run on IE11 and use existing AMD dependencies such as dojo and dstore.

As far as I can tell, the general steps involved are:

1. Roll up all the functional test files into a single Storybook-like "application".
2. Convert AMD code to ES6 using https://www.npmjs.com/package/amd-to-es6.
3. Add actual webpack build, following pattern in https://github.com/theintern/intern-examples/tree/master/webpack-example.

The conversion then needs to be done for all downstream projects (including deliteful and dcalendar).