[ingo] removing default rule buttons

[amy.rich@tufts.edu]

nicolas.schmitz> You can't set it to ''...  Maybe try with :
nicolas.schmitz>  'value' => 'a:0:{}',

Ah, right, my mistake (I should have looked at the whitelist array as an
example).  However, that still does not get rid of the buttons across the
top.  In addition, when I click on "New Rule" it logs the error:

PHP Notice:  Undefined variable:  rule_url in
/usr/local/apache/htdocs/horde/ingo/templates/filters/footer.inc on line 13