add baseGroupDn in archiva configuration

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1444880 13f79535-47bb-0310-9956-ffa450edef68
save groups baseDn via the ui

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1444881 13f79535-47bb-0310-9956-ffa450edef68
verify ldap groups dn too

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1444882 13f79535-47bb-0310-9956-ffa450edef68