Revise cookbook list item design on the desktop

The new design is based off of Corey's mock-up, which is attached to a
[Trello card].

- Position cookbook updated timestamp after name/version
- Add font-awesome icon to cookbook version
- The version and timestamp are visually separated from the title.
- Move cookbook title into cookbook_header
- Move cookbook owner gravatar to header
- Decrease cookbook description font size
- Remove min-height on cookbook partial content
- Supported Platforms header precedes icons and is uppercase
- Add more space between platform icons and header
- Move cookbook stats into footer content
- Add icons to each stat
- Add a follow button the cookbook partial footer
- Correctly pluralize/singularize Follower/Download
- Remove cookbook partial sidebar
- Make the cookbook header background white
- Give cookbook maintainer gravatars a box shadow
- Replace '>' with HTML entity in twiddle-wakka

[Trello card]: https://trello.com/c/06QCB0Dr
Revise cookbook list item mobile styles
Merge pull request #381 from opscode/cookbook-partial-style-update

Update cookbook partial style