Use a button to destroy officials

As mentioned in commits 5311daadf and bb958daf0, using links combined
with JavaScript to generate POST (or, in this case, DELETE) requests to
the server has a few issues.

app/assets/stylesheets/admin/action.scss

@@ -3,4 +3,8 @@
   &[disabled] {
     @include button-disabled;
   }
+
+  &.delete {
+    cursor: pointer;
+  }
 }