add an admin user "demo" with password "guest" to run test requiring login

.travis.yml

@@ -55,9 +55,10 @@ before_script:
 
 script:
   # install egroupware using MariaDB as domain "default"
-  # disable MariaDB install as it fails after some changes in Travis environment
+  # and add an admin user "demo" with password "guest"
   - php doc/rpm-build/post_install.php --domain default
     --source_dir `pwd` --start_db '' --autostart_db '' --start_webserver '' --webserver_user ''
+    --admin_user demo --admin_passwd guest
   # disable PostgreSQL install as it fails in Travis with Fatal error: Call to unimplemented native function pg_set_client_encoding
   # install egroupware using PostgreSQL as domain "pgsql", need some specific handling we can not create users via sql
   #- psql -U postgres -c 'create database egroupware';