Move the stylesheets out stylesheets/libs.

This is the first step in better organizing the stylesheets to be broken apart
into separate files to be more digestible.
Split apart the cookbooks stylesheet.

Create smaller files logically named by the areas of Cookbooks they pertain to.
Sprockets requires_tree for the cookbooks styles, meaning that any file added to
the folder will automatically be included.
Remove empty globalcolumn stylesheet.
Move the user styles into a directory.
Increase the capybara timeout.
Merge pull request #391 from opscode/split_up_stylesheets

Split up the Supermarket stylesheets to be more digestible
Adjust the bottom margin for tab dds.

This fixes the style issue where a border-bottom was still displayed on active
tabs.