LDAP auto refresh of information

Just as a heads up for prospective new users who do a fresh install
of Request Tracker with LDAP integration.

In order for the ExternalAuthentication - Request Tracker Wiki integration
to automatically update/refresh data from LDAP, the user must have
ModifySelf rights.

Without this right the code will happily state UPDATED in the logs
even though it was denied permission to set the values.