Node/npm package support

[p-decoraid]

This is a superset of #245, it does:

1. Rename package to sly-scrolling;
2. Create another distribution file, sly.node.js, which exports Sly without bindings to global jQuery or window objects (#244 requests this);
3. Adds documentation for using the package in a Node environment.

Try it out with npm install @rq/sly-scrolling (https://www.npmjs.com/package/@rq/sly-scrolling).

[decease]

👍