Update application.css.

* clean up unused class and inherited properties
* move `.button` along with the rest of the selectors from that page
* remove `-moz-inline-stack` which was needed for old FF
Use qTip from the first mirror instead of the cloudflare distribution.
Work around issues with old IE.
Remove selectivizr-min.js.

It's not needed anymore as things work pretty good with old browsers.