Implement %Attr.AllowedClasses and %Attr.ForbiddenClasses.

Signed-off-by: Edward Z. Yang <edwardzyang@thewritingpot.com>

library/HTMLPurifier/HTMLModule/CommonAttributes.php

@@ -8,7 +8,7 @@ class HTMLPurifier_HTMLModule_CommonAttributes extends HTMLPurifier_HTMLModule
         'Core' => array(
             0 => array('Style'),
             // 'xml:space' => false,
-            'class' => 'NMTOKENS',
+            'class' => 'Class',
             'id' => 'ID',
             'title' => 'CDATA',
         ),
@@ -20,6 +20,7 @@ class HTMLPurifier_HTMLModule_CommonAttributes extends HTMLPurifier_HTMLModule
             0 => array('Core', 'I18N')
         )
     );
+
 }
 
 // vim: et sw=4 sts=4