Move Assets::Helpers to Assets:SassHelpers.
Rename current_user to current_admin in ApplicationHelpers.
Move assets url logic to Assets module.
Use SecureRandom in Admin.
Require just "lib/assets" in Rakefile.
Move rake and sprockets out of default Gemfile group. They are not required in production.
Set require option for sinatra and sinatra/flash.
Require all gems using Bundler.setup.
Remove bundler setup from config.ru.
Assets::Environment requires sprockets and sass_helpers.
Assets::Manifest does not need environment.
Write some comments about assets modules and classes.
Assets::Manifest requires sprockets/manifest.
Assets::Manifest does not requires ostruct anymore.
Require Assets::Environment only in development and test environments.
Use default manifest for assets compilation.
Put rake back to Gemfile default group, but with require false.
Increase titles line-height.
Update sinatra.
Replace R18n gem by I18n.