Red Cosmetics v2

Having upgraded to Bootstrap v2.3.1, reworked the nav-tabs customisation to make the CSS selectors more like the bootstrap one. Changed hover to fit in with the great new "dark tabs" style. Made tabs 2px taller which still allows two rows but improves appearance.

The only change I've noticed in Bootstrap v2.3.1 that affects Red is a small increase in btn-large height due to an increase in padding. Have overridden this in .btn.rascal (in editor-all.css) to avoid increasing height of button bar.