Add "change management" privilege to the Admin Console

LBG is requiring to have a specific "change management" privilege to limit access to "Maintenance Updates" pages only in their Administrative Console. Currently "Super user" privileges are needed with a full control in the entire Administrative functionalities.

This is needed to all clients where GTS is involved as client's Service management and this enhancement is the lonely way to delegate GTS to manage maintenance updates to LBG since they does not agree to give full control of them.