Store the maximum uid for the next user

[hakasapl]

We should use sql to store the maximum used uid/gid and pi uid and gi uid number for the next bew group to use to avoid new groups being created on older IDs.

[hakasapl]

Make a sitevars table in mysql with columns: id, name, value. In this case, a row would be: ID, MAX_UID, 1855

For GID: ID, MAX_GID, 1855
PIGID: ID, MAX_PIGID, 10032

Change occurs in resources/lib/UnityLDAP.php. Interact w/ UnitySQL.php. Function in UnityLDAP to change is getNextUIDNumber(), getNextGIDNumber(), getNextPIGIDNumber()