Add copy about deprecation to the modal.
Create the deprecate_search internal end-point

Create a unique search end-point in order for Cookbook deprecation select2
search to only return eligible cookbooks for deprecation. A cookbook is elgible
for deletion if it is not deprecated and not the cookbook to be deprecated.

Notes:

- the code in the controller should be moved into an instance method on cookbook
- the deprecation parts of the CookbooksController could be broken out into
  their own controller to KISS
- the enforcement of not replacing a cookbook w/ an already deprecated cookbook
  should be enforced at the Cookbook#deprecate level as well
Handle deprecation failure at the controller level

This could be improved by:

- improving Cookbook#deprecate to use record.save! and rescue from the error
- displaying the actual error
Implement Cookbook#deprecate_search

Move the logic from the CookbooksController#deprecate_search into an instance
method on Cookbook.
Only allow deprecation if replacement selected
Default deprecate_search q param to nil.
Merge pull request #635 from opscode/cookbook_deprecation_adjustments

Cookbook deprecation adjustments