Remove ie8 css/js

- removed css contents referencing IE6/7/8 thus fixes #7333
- core css/ie7 and css/ie8 are stripped of css, are no longer registered as simplecache urls, are no longer referenced in page head and are deprecated (if someone should directly use them)
-  also removed the ie7 css from the aalborg theme
- removed some old ie8 fix in groups (odd/even classes)

We don't support IE9 either :)