Add instructions to README on how to add ArcGIS to a new angular-cli app

[tomwayson]

29 highlights the need for instructions that shows the minimal steps to start using the ArcGIS API in an angular-cli app rather than leaving it up to devs to reverse engineer from this increasingly complex example app. Something that starts where the angular-cli instructions for creating a new app leaves off and walks devs through these steps:

1. installing angular2-esri-loader
2. registering that service w/ the app's DI
3. create a new map route (optional?)
4. create a new component that uses the service to show a map

I think the instructions and required code snippets could live in a gist and we'd just link to that from the README of this app.

[tomwayson]

A better idea is to help @jwasilgeo make his gist on how to add esri libraries to angular2-webpack-starter more generic so it applies to angular-cli as well. Then just link to that from the README.

[jwasilgeo]

@tomwayson please take another look now, and feel free to edit the gist.