adapt README and BUILDING for 'sub' npm pacakges

... and refactor "Quick start options" section. List CDN first,
  plotly.js-dist 2nd and github release 3rd

Author: etpinard

BUILDING.md

@@ -1,5 +1,7 @@
 # Building plotly.js
 
+The easiest way to bundle plotly.js into your application is to use the one of the distributed plotly.js packages on npm. These distributed packages should just work with **any** build framework. That said, if you're looking to save a few bytes, read the section below corresponding to your building framework.
+
 ## Webpack
 
 For plotly.js to build with Webpack you will need to install [[email protected]+](https://github.com/hughsk/ify-loader) and add it to your `webpack.config.json`. This adds Browserify transform compatibility to Webpack which is necessary for some plotly.js dependencies.

README.md

@@ -32,48 +32,45 @@ and more.
 
 ## Quick start options
 
-#### Download the latest release
-[Latest Release on Github](https://github.com/plotly/plotly.js/releases/)
+#### Use the plotly.js CDN hosted by Fastly
 
-and use the plotly.js `dist` file(s). More info [here](https://github.com/plotly/plotly.js/blob/master/dist/README.md).
+```html
+<!-- Latest compiled and minified plotly.js JavaScript -->
+<script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
 
-#### Clone the repo
+<!-- OR use a specific plotly.js release (e.g. version 1.5.0) -->
+<script src="https://cdn.plot.ly/plotly-1.5.0.min.js"></script>
 
-```bash
-git clone https://github.com/plotly/plotly.js.git
+<!-- OR an un-minified version is also available -->
+<script src="https://cdn.plot.ly/plotly-latest.js" charset="utf-8"></script>
 ```
 
-and use the plotly.js `dist` file(s).
+and use the `Plotly` object in the window scope.
 
 #### Install with `npm`
 
 ```bash
-npm install plotly.js
+npm install plotly.js-dist
 ```
 
-and require plotly.js using CommonJS as `var Plotly = require('plotly.js');` or use the plotly.js `dist` file(s).
+and import plotly.js as `import Plotly from 'plotly.js-dist';` or `var Plotly = require('plotly.js-dist');`.
 
-#### Use the plotly.js CDN hosted by Fastly
-```html
-<!-- Latest compiled and minified plotly.js JavaScript -->
-<script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
-
-<!-- OR use a specific plotly.js release (e.g. version 1.5.0) -->
-<script src="https://cdn.plot.ly/plotly-1.5.0.min.js"></script>
+#### Download the latest release
 
-<!-- OR an un-minified version is also available -->
-<script src="https://cdn.plot.ly/plotly-latest.js"></script>
-```
+[Latest Release on Github](https://github.com/plotly/plotly.js/releases/)
 
-and use the `Plotly` object in the window scope.
+and use the plotly.js `dist` file(s). More info [here](https://github.com/plotly/plotly.js/blob/master/dist/README.md).
 
 ##### Read the [Getting started page](https://plot.ly/javascript/getting-started/) for more examples.
 
+
 ## Modules
 
-Starting in `v1.15.0`, plotly.js also ships with several _partial_ bundles (more info [here](https://github.com/plotly/plotly.js/blob/master/dist/README.md#partial-bundles)).
+Starting in `v1.15.0`, plotly.js ships with several _partial_ bundles (more info [here](https://github.com/plotly/plotly.js/blob/master/dist/README.md#partial-bundles)).
+
+Starting in `v1.39.0`, plotly.js publishes _distributed_ npm packages with no dependencies. For example, run `npm install plotly.js-geo-dist` and add `import Plotly from 'plotly.js-geo-dist';` to your code to start using the plotly.js geo package.
 
-If you would like to manually pick which plotly.js modules to include, you can create a *custom* bundle by using `plotly.js/lib/core`, and loading only the trace types that you need (e.g. `pie` or `choropleth`). The recommended way to do this is by creating a *bundling file*:
+If you would like to manually pick which plotly.js modules to include, you'll first need to run `npm install plotly.js` and then create a *custom* bundle by using `plotly.js/lib/core`, and loading only the trace types that you need (e.g. `pie` or `choropleth`). The recommended way to do this is by creating a *bundling file*. For example, in CommonJS:
 
 ```javascript
 // in custom-plotly.js