Created Basic Issue Template

inspired by webpack's issue template

Remove heavy examples and demo data from npm package distribution

Fix README "10 lines" example

Update A-Frame docs.

Change `artoolkit` to new `arjs` system, update `debug` to `debugUIEnabled` (could probably be shortened to `debugUI`?), and change example `<a-cube>` to `<a-box>`, as that's the valid markup in A-Frame.

Conflicts:
	aframe/examples/demo-3dio/basic.html