GH96: ACL improvements

-- DB UPDATE --

CREATE TABLE `users_roles` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `role` varchar(63) NOT NULL,
  `description` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

alter table users add role_id int NOT NULL default 1; ##role_id=1 always should be Guest role

insert users_roles VALUES (0, 'Guest', 'Role with limited access. Could only view messages and has no access to pages which required authorization!'), (0, 'User', 'Ordinary user. Administrator functions are disabled!'), (0, 'Administrator', 'All features are available. No Restrictions are applied. Full access granted!!!');

-- END OF DB UPDATE --
GH96: ACL improvements

Fixed comments of George. Made optimization.
Merge pull request #117 from 35aa/GH96

GH96: ACL improvements