Bring back checkmark icon on successful update

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

core/css/guest.css

@@ -434,7 +434,7 @@ form #selectDbType label.ui-state-active {
 	border-radius: 3px;
 	cursor: default;
 }
-.warning, {
+.warning {
 	padding: 5px;
 	background: #fdd;
 	margin: 0 7px 5px 4px;
@@ -541,6 +541,9 @@ p.info {
 .icon-confirm-white {
 	background-image: url('../img/actions/confirm-white.svg?v=2');
 }
+.icon-checkmark-white {
+	background-image: url('../img/actions/checkmark-white.svg?v=1');
+}
 
 
 /* Loading */