Add titles and descriptions to applicable views.
Merge pull request #230 from opscode/titles

Add titles and descriptions to applicable views.
Cookbook source url and issues url can be managed.

- Add UI on cookbook show
- Rename 'external_url' to 'source_url' on Cookbook.
- Add 'issue_url' attribute to Cookbook.
Merge pull request #212 from opscode/manage_cookbook_urls

Users can manage cookbook url data
Update Virtus.
Add breadcrumbs to Cookbook show.
Merge pull request #232 from opscode/update_virtus

Update Virtus.
Merge pull request #233 from opscode/cookbook_show_breadcrumbs

Add breadcrumbs to Cookbook show.
Implement cookbook following

Implement the ability for users to follow a cookbook. Users may click
Follow from the cookbook show view and a remote request is sent to
/cookbooks/:cookbook/follow a 200 response is returned if it is
successful.
Build out follow feature a bit more.
Add unfollowing and unauthenticated following flow.
Some style cleanup.
Use RJS.