def create
      @invitation = Invitation.find(session[:invitation_id])
      @response = @invitation.responses.build(params[:response])
      if @response.save
        redirect_to confirmation_response_index_path
      else
        render :action => :index
      end
    end
def create
      @invitation = Invitation.find(session[:invitation_id])
      @response = @invitation.responses.build(params[:response])
      if @response.save
        redirect_to confirmation_response_index_path
      else
        render :action => :index
      end
    end
POST /response