Improve documentation and Integrate automated code docs

[ygongdev]

I'm thinking something along the lines of JSDoc...?

[grapho]

Speaking of documentation.. what is the status of test helpers? Importing via import { drag } from 'ember-sortable/test-helpers does not work as documented. I'm getting "module not found" error on 2.0.1

[knownasilya]

looks like it's now import { drag } from 'ember-sortable/test-helpers/drag'; Not sure if that was on purpose or an accident. Personally I prefer the old pattern for related things.

[ygongdev]

@grapho Does import { drag } from ember-sortable/test-helpers/drag work? Looks like we need to re-export it from ember-sortable-test-helpers to make it easier.

[ygongdev]

Regardless I'll have some more time to play with this as I integrate this library into my own app. Will update the README once I figure out what final behavior should look like.

[ygongdev]

@grapho My bad, my oversight. #328 should allow you to do

import { drag, reorder } from ember-sortable/test-support/helpers;