added:
 - It is now possible to use standard LDAP filters for filtering
services in UniPlayer scenarios. The filter is allways build as
"(&(objectclass=service_class)(user_filters))" where service_class is
the "service" attribute of "call" element and user filters is "filter"
attribute if "call" element. When the filter attribute is not used,
services are retrieved only by the class name under which they were
registered.