Increment web_download_count instead of download_count
The API file download URL is distinct from the web URL
Track API download counts in the API download action
API downloads redirect directly to a tarball
The SegmentIO agent keeps track of the last event tracked
Test that the API downloads are tracked in SegmentIO
Test that web downloads are tracked in SegmentIO
Encapsulate aggregate download statistics
Compute a cookbook version's download count in-memory
Compute a cookbook's download count in-memory
Order cookbooks by their segmented download counts
Remove the now-unused download_count columns
Adjust the bottom margin for tab dds.

This fixes the style issue where a border-bottom was still displayed on active
tabs.
Merge pull request #392 from opscode/fix_active_tab_style

Adjust the bottom margin for tab dds.
Merge pull request #393 from opscode/segment-downloads-by-api-and-web

Segment downloads by API and web
Only use Poltergeist to drive features when needed

When writing feature specs, the Rack::Test driver is used by default. If the
Poltergeist driver is required to be used, add the +use_poltergeist: true+
metadata to the spec.

This should improve the performance when running feature specs. It should
decrease the opportunities of Capybara timing out when Travis CI runs specs.

Note: because of this switch, it is required to be more specific about elements
that occur multiple times on a page. For example, this may require using within
blocks.
Merge pull request #397 from opscode/adjust_feature_spec_driver

Only use Poltergeist to drive features when needed
Improve responsiveness

Improves the responsiveness throughout the application, specifically:

- Adjust directory so columns line up on small screens.
- Adjust cookbook header so follow button doesn't fall off.
- Ensure cookbook sidebar has padding at the top.
- Improve look, feel and responsiveness of welcome view.
- Add wrapper class for welcome page.
- Adjust edit cookbook look so there aren't so many buttons flying around.
- Adjust font size for better readability on smaller displays.
- Fix some minor display bugs that appear on smaller displays.

Clean up stylesheets to try to adhere to code style guide.