Adding typescript and rollup

[weaverryan]

This converts the project to Typescript and uses rollup to:

A) build the src/index.ts file with esm B) build the src/webpack/lazy-controller-loader.ts - which is used as a Webpack loader - into cjs, just so that it can be parsed by Node without the user needing typescript.

TODO:

• [x] Fix ESLint errors
• [x] Fix a webpack loader problem
• [ ] Ideally silence some/all Typescript warnings

[tgalopin]

Thanks @weaverryan.