Remove W3C and SourceForge logos from footer

This commit removes the W3C and SourceForge logos from page footer, making page load faster because of the removed connection to two external server (http://www.w3.org/Icons/valid-html401 and http://sflogo.sourceforge.net/sflogo.php?group_id=87163&type=10).
Removing SourceForge logo removes also user tracking by SourceForge.