Meta server: Fix group table limit enforcement by checking the size of the corresponding table. Re-implement meta server admin and stat users and group logic, by moving it into user and group class, in order to simplify the parameter and user and group data bases update propagation. The new implementation updates "stats" and "admin" user mapping immediately after the user and group table get updated, and makes the updated information available on then next net manager's run loop iteration. Make admin and stats user id lookup more efficient by creating and using single user id lookup table. One table for each category:stats and admin.