silence_assets.rb

# Very slightly modified version of this solution: http://stackoverflow.com/a/7508407/294449

Rails.application.assets.logger = Logger.new('/dev/null')

class Rails::Rack::Logger
  def call_with_quiet_assets(env)
    previous_level     = Rails.logger.level
    Rails.logger.level = Logger::ERROR if env['PATH_INFO'].match(/\/assets\//)

    call_without_quiet_assets(env).tap do
      Rails.logger.level = previous_level
    end
  end

  alias_method_chain :call, :quiet_assets
end