Set Cache-Control headers
Refactor lib/assets to store digests in a single manifest file
Add app_last_modified method based on the mtime of asset-manifest.yml
Add blank? and present? methods from Rails' Object extension
Set JS vars for github_id and gravatar_id with cookies rather than inline in the HTML payload
Refactor cookie setting
Move the GitHub login logic back to the client-side—again
Properly destroy the cookies upon logout
Move the building of the cloud menu to JS
Remove can_update_gist, as it is user-specific and not cacheable
Merge branch 'better-caching'