fix redirect issue with easing

Currently in the application I'm working on with this theme I use GitHub OAuth2 which redirects after a successful authorization. When GitHub (or any OAuth protocol) redirects this function executes before .page-scroll a is visible in the DOM regardless of document.ready. The click handler should be bound to the listen on the body for clicks to .page-scroll a instead. While this might be a little more expensive than binding to the actual element it fixes a pretty large problem IMO. It's a double edged sword because either you sacrifice a little bit of optimization or easing breaks when a server redirects the app. Even though I realize this is supposed to be a single page template I think login/OAuth is the one exception.