Code: add unit tests to aid innovation without regressions

[nfreear]

To implement issue #12 I'll need to re-arrange the vanillajs code somewhat. So I thought this would be a good time to include some unit tests.

I propose using a lightweight framework initially - BusterJS, hosted via CDN.

However, I suggest we make it fully automated in time, perhaps using Grunt, PhantomJS etc. Note, I don't want to make the project top-heavy. The currently Javascripts are lightweight, and good at doing one job. It would be a pity to add lots of supporting files...

Thoughts welcome!

[nfreear]

Unit test related edits in,

• nfreear/accessifyhtml5.js@5d718ad

Using asserts.tagName() - buster-assertions

[nfreear]

To assess the state of Buster.js on Windows/ Internet Explorer (nfreear/accessifyhtml5.js@679125d9e11de668), see

• http://docs.busterjs.org/en/latest/developers/windows