Accessibility enhancements, creates a figure element with an optional ca...

Full list of changes:

* changed the #holder to a `<figure>` element
* added a little default styling to the table on the example for non-supporting browsers
* made minor, non-impacting changes to the table markup.
* added aria role of `image` on the `<figure>`
* creates a `<figcaption>` if the source table has a `<caption>`
* fakes an ID on `<figcaption>` so that the `<figure>` can reference it with `aria-labelledby`

Also adds some project files like .gitignore, etc.

One outstanding feature request:  For some reason the source table is completely replaced by the bar graph. For accessibility it'd be cool to have a show/ hide for this table. Screen reader users would probably find the existing table to be more useful.  For some reason I'm not smart enough to make the table show.