change_list.html template: breadcrumb and object tool permisson

1. breadcrumb: `app_label` doesn't seem to be sat in Django 1.7, use `cl.opts.app_config.verbose_name`;

2. In current version, object tool will not show if the user don't have `add` permission to the model. Since object tool has its own permission, we may better just validate against it. So a minor adjustments was made for this.

3. sorry for late response. The previous pull request break backward compatibility.