Use a different OpenLDAP docker image for testing

because openshift/openldap-2441-centos7 reports 404

Author: atodorov

docker-compose.testing

@@ -3,11 +3,16 @@ version: '2'
 services:
     openldap_server:
         container_name: openldap_server
-        image: openshift/openldap-2441-centos7
+        image: bitnami/openldap
         restart: always
         ports:
             - 389:389
             - 636:636
+        environment:
+            - LDAP_PORT_NUMBER=389
+            - LDAP_LDAPS_PORT_NUMBER=636
+            - LDAP_ADMIN_USERNAME=admin
+            - LDAP_ADMIN_PASSWORD=admin
 
     db:
         container_name: db