Create the cookbook deprecated email.
Create the cookbook deprecated notifier worker.

This loops through all users who should receive an email when a cookbook is
deprecated: the owner, collaborators and followers of a cookbook. Of course, it
is only those who opted into receiving emails.
Kick off the cookbook deprecated notifier

When the Cookbook#deprecate controller action is called, kick off an email
worker before redirecting.
Make CookbookDeprecatedNotifier spec more explicit
Merge pull request #610 from opscode/cookbook_deprecation

Cookbook deprecation emails