With this function you can set the maximum expire time that is used by auth to a new value.
expiration time, number of seconds
if TRUE $time is added to the existing expiration time, if FALSE the exitsing time value will be replaced.
This function can not be called statically.
Auth uses PHP's session mechanism to recognize users between http calls. Setting Auth's expiry time larger than the session timeout will still expire the session to the time the php session expires.