Added function "is_superadmin" in auth library and improved other functions.

Till Brehm

2014-08-13 19b5e01da02aa2115ee802cf2e43a7f3e58f4eac

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ALTER TABLE  `sys_session` CHANGE  `session_id`  `session_id` VARCHAR( 64 ) CHARACTER SET latin1 COLLATE latin1_swedish_ci NOT NULL;