Usage: gms_admin_ban ( player_id, reason, days )
Bans the given player for 'days' days, and kicks him.
'reason' is optional, and can be used to send the player a last message before getting kicked.
This function can be executed on every client, even guests. You'll need to check by using server_self_admin_rights
whether the player is authorized to ban someone.
Last message on 3 Oct 2014