Provide current and next links to views_infinite_scroll_updated trigger

The views_infinite_scroll_updated hook is a great way to run code after the scroll has been loaded, but it doesn't contain information on what page has just been loaded. The load function of autopager.js provides for this (http://lagoscript.org/jquery/autopager/documentation), so let's add support for it into views_infinite_scroll. (This hook is provided via the patch in http://drupal.org/node/1806628#comment-7062676)