move desktop mode to user pref

app/controllers/users_controller.rb

@@ -1,7 +1,6 @@
 class UsersController < ApplicationController
   respond_to :html, :xml, :json
   skip_before_filter :api_check
-  before_filter :process_session_actions, only: [:update]
 
   def new
     @user = User.new
@@ -79,16 +78,6 @@ class UsersController < ApplicationController
 
 private
 
-  def process_session_actions
-    if params[:user].has_key?(:desktop_mode)
-      if params[:user].delete(:desktop_mode) == "0"
-        cookies.delete(:dm)
-      else
-        cookies[:dm] = "1"
-      end
-    end
-  end
-
   def check_privilege(user)
     raise User::PrivilegeError unless (user.id == CurrentUser.id || CurrentUser.is_admin?)
   end