switching page_cache_path for pc and mobile

application_controller.rb

class ApplicationController < ActionController::Base
  include Mobylette::RespondToMobileRequests
  ...
  protected
  def cache_page_with_mobile_feature(content = nil, options = nil, gzip = Zlib::BEST_COMPRESSION)
    prefix = params[:format] == 'mobile' ? '/mobile' : '/pc'
    path = "#{prefix}#{request.path}"
    cache_page_without_mobile_feature(content, path, gzip)
  end
  alias_method_chain :cache_page, :mobile_feature
end