make notification call explicit

The version of Chef that AWS's OpsWorks employs does not handle the `notifies` calls with implicit resource shortcuts.  This issue is outlined [here](https://github.com/aws/opsworks-cookbooks/issues/28#issuecomment-17371664).

Accepting this pull request will not materially change the makeup of the cookbook and will ease the bleeding-edge users of AWS OpsWorks.  Ultimately, OpsWorks will upgrade Chef and this will be a non-issue.  But, until then, this pull request will help myself and others.