package/screenshot association added.
Added screenshot.url method to get a relative link to a screenshot
Association from Package->Screenshots added
Added Package.with_screenshots to get a query of packages that have screenshots
Old workaround comment for Sequel removed. Bug was fixed.
Added Package.best_screenshot to find the newest screenshot
Removed database schema cruft (only needed for ActiveRecord - not for Sequel)
Showing proper screenshots from database data on the home screen
Better display of screenshot thumbnails in grid view