pptp: can now print more dramatic messages

src/www/vpn_pptp.php

@@ -307,14 +307,15 @@ function enable_change(enable_over) {
 				<?php if (isset($savemsg)) {
                     print_info_box($savemsg);
 } ?>
-				<?php print_info_box(
+				<?php print_alert_box(
 					gettext(
 						'PPTP is not considered a secure VPN technology, because it relies upon ' .
 						'the compromised MS-CHAPv2 protocol. If you choose to use PPTP, be aware ' .
 						'that your traffic can be decrypted by virtually any third party. ' .
 						'It should be considered an unencrypted tunneling protocol.'
 					) .  ' <a href="https://isc.sans.edu/diary/End+of+Days+for+MS-CHAPv2/13807">' .
-					gettext('Read more') . '</a>.'
+					gettext('Read more') . '</a>.',
+					'danger'
 				); ?>
 
 			    <section class="col-xs-12">