make it work in standard mode (instead of quirks mode)

In standard mode, you can't have unitless style.left/right..

Example file was in quirks mode, was misleading. Beofre this PR,
slideways is likely to work only on pages that are in quirksmode, thus
not a lot of pages.

https://developer.mozilla.org/en-US/docs/Mozilla_Quirks_Mode_Behavior
has a reference to the 'px' only added in quirksmode automatically.

Tested in chrome latest and IE9, I guess it's ok everywhere else.

This PR is similar to #1 but less noisy
insert-css, domify, brfs, running example

- use substack/insert-css, in prepend mode
- use domify instead of hyperglue (no need for hyperglue layer)
- use brfs instead of custom js modules
- make example easier to run
- remove "opts.insertCss" feature. Since we prepend the css to the DOM,
we are now a true "widget" with easy cascading styling