Fixes for header, footer, and jQuery 

Fixes issues related to/noticed when testing the header, footer, and jQuery update.

* Make it so you can access drop down menus even from the current page (aka remove span_if_current from primary links; most noticeable with Hi, username! menu)
* Remove styles from the old footer that were causing the new one to display incorrectly in IE8 and lower
* Change the Volunteer link text under About to Donate or Volunteer
* Change the Tag Wrangling link in Hi, username! to point to the user's tag wrangling home
* Add Invite Users link to the admin header
* Set a maxwidth on the search tooltip to prevent horizontal scrolling in Firefox
* Fix some broken HTML on the invite requests page that was causing display issues in Opera
* Reorder the navigation buttons on the various search pages so they are in the same order as the links in the search drop down menu
* Fix scrollTo for pagination of AJAX comment pages and move scrollTo-related JavaScript to the commentable partial, since it is only used in that location
* Add Get Invite link to the Log In menu
* Change CSS for drop down menu background so the drop down menus have background colors when images are disabled in Opera
* Shrink site logo image so it displays nicer on Windows and tweak mobile stylesheet so the new image displays correctly there
* Add menuitem role to drop down menu items to better adhere to ARIA standards
* Move the JavaScript for the drop down menus up so it loads earlier
* Stop loading qTip JavaScript on every page, since it already loads on the tag set nominations page where it is needed
* Stop including the LiveValidation JavaScript in the _javascripts partial, since it's already in the page head and loading it twice means it doesn't work
* Move Known Issues link in the footer to the Development section
* Fix some logic that was breaking the footer HTML, possibly just in devmode