03-internals.md listeners example no longer refers to nonexistent 'complete' attribute.
Merge pull request #384 from dcmaf/gh-pages

Chapter 1: Introduction - Fixed typos and punctuation
Merge pull request #388 from jan-molak/gh-pages

Corrected 'complete' to 'completed' in 03-internals/listeners code example
For #333 - adds new comment lines for changes to view
For #348: Corrections to model examples, changing hint comments to be more readable, adding a few extra comments to examples
Fixes #337 - adds a number of sane changes to allow the first examples to be run
Fixes #386 - adds boilerplate, links to jsfiddle/bin, instructions for console testing for internals chapter
Fixes #362 - adds extended paragraphs about the extensions chapter
Prelude: rewrote opening few paragraphs to try to make it stronger
and "drive the point home" as requested in Jeremy's review.