Validate date/time settings when typed in directly.

The changeTime event isn't fired when the user types in the field, but
only when clicking on the time in the dropdown. I'd consider this a
timepicker bug, but for now we can just listen to the user typing in
the field and update the value (and thus validate) like we do with
other field types.

cms/static/js/views/settings/main_settings_view.js

@@ -107,6 +107,7 @@ CMS.Views.Settings.Details = CMS.Views.ValidatingView.extend({
         // to pick up when the date is typed directly in the field.
         datefield.change(setfield);
         timefield.on('changeTime', setfield);
+        timefield.on('input', setfield);
 
         datefield.datepicker('setDate', this.model.get(fieldName));
         // timepicker doesn't let us set null, so check that we have a time