Highlight menu item for the current page or page subsection.

Also moves IE8 conditional comments inside the site_js block for better
control in child templates.
Only show apply button in university page if there are internships.

Also: 
- Adds a GET parameter for testing the messaging manually.
- Change apply now links to scroll to message at bottom of university 
  page if no positions are available.
Fix bug 914839: Bay Area, North America, Europe, Latin America filters.