create a set of signed Amazon CloudFront
cookie parameters @param [String] url @option params [Time, DateTime, Date, String, Integer<timestamp>] :expires @option params [String<JSON>] :policy
def signed_cookie(url, params = {})
content = {}.tap do |c|
if params[:policy]
c[:policy] = params[:policy]
elsif url && params[:expires]
scheme, uri = scheme_and_uri(url)
c[:resource] = resource(scheme, uri)
c[:expires] = time(params[:expires])
end
end
cookie_parameters = {}
signature(content).each { |k, v|
cookie_parameters["CloudFront-#{k}"] = v.to_s.gsub("\n", '')
}
cookie_parameters
end