message: Fix spelling of dismissible
diff: {{#each messages as |stat|}}
  {{#bs-alert
  type=stat.class
  - dismissable=stat.dismiss
  + dismissible=stat.dismiss
  classNames=(if stat.jumbo (local-class 'StatusBanner__jumbo'))
  }}
  <div class="{{if stat.jumbo 'jumbotron'}}">
  