add more caching for ldap roles

git-svn-id: https://svn.apache.org/repos/asf/archiva/redback/redback-core/trunk@1437804 13f79535-47bb-0310-9956-ffa450edef68
honor useDefaultRoleName when searching all roles/groups from ldap

git-svn-id: https://svn.apache.org/repos/asf/archiva/redback/redback-core/trunk@1437805 13f79535-47bb-0310-9956-ffa450edef68
remove duplicate code

git-svn-id: https://svn.apache.org/repos/asf/archiva/redback/redback-core/trunk@1437806 13f79535-47bb-0310-9956-ffa450edef68