bugfix: class gets constructed at init, so adding an init action in the constructor results in that action not being called. init code has to be called directly inside the constructor

git-svn-id: https://plugins.svn.wordpress.org/wp-performance-pack/trunk@888633 b8457f37-d9ea-0310-8a92-e5e31aec5664
bugfix: use network_admin_menu to add menu page in multisite network mode

git-svn-id: https://plugins.svn.wordpress.org/wp-performance-pack/trunk@888636 b8457f37-d9ea-0310-8a92-e5e31aec5664