fix issue 116 by adding href="#" to buttons, improving general accessibility
Correct all <a> buttons which don't have an `href`

This also switches <a> buttons to <buttons> where appropriate.

Fixes #116
Merge branch 'button-href' of git://github.com/tilomitra/pure-site into pure-0.2.0

Conflicts:
	views/partials/buttons/disabled.handlebars
Move prevent-scroll JavaScript partial outside main content <div>