Add a default icon for the fan component (#101)

src/util/hass-util.html

@@ -217,6 +217,9 @@ window.hassUtil.domainIcon = function (domain, state) {
     case 'device_tracker':
       return 'mdi:account';
 
+    case 'fan':
+      return 'mdi:fan';
+
     case 'garage_door':
       return 'mdi:glassdoor';