add unit test for LdapGroupMappingService

git-svn-id: https://svn.apache.org/repos/asf/archiva/redback/redback-core/trunk@1441485 13f79535-47bb-0310-9956-ffa450edef68
really add test !

git-svn-id: https://svn.apache.org/repos/asf/archiva/redback/redback-core/trunk@1441486 13f79535-47bb-0310-9956-ffa450edef68