Switch to webpack and npm workflow

**WARNING: Early preview. Do not merge.**

To get started with the example run:

```bash
$ git clone git://github.com/tidepool-org/tideline.git
$ cd tideline/
$ git fetch origin nico/workflow
$ git checkout -b nico/workflow origin/nico/workflow
$ npm install
$ npm start
```

**Progress**:

- [x] Use npm for vendor packages, replace `window.<lib>` with `require('<lib')` in source code
- [x] Remove unused `src/lib` for vendor packages
- [x] Use webpack to bundle images
- [x] Use webpack to bundle fonts in example
- [x] Use `webpack-dev-server` for development on example
- [x] Use `envify-loader` to define data file via `DATA` environment variable
- [x] Update `README`
- [ ] Update tests to work with webpack
- [ ] Verify `gh-pages` workflow still works
- [ ] Cleanup: Bower files, develop and build scripts, remove unused from package.json, update .gitignore, etc.