Remove old docker instruction

Author: frankdejonge

.travis.yml

@@ -40,7 +40,6 @@ install:
 
 before_script:
   - docker-compose -f tests/docker-compose.yml up -d
-  - docker run -d --name ftpd_server -p 21:21 -p 30000-30009:30000-30009 -e "PUBLICHOST=localhost" stilliard/pure-ftpd:hardened
   - php wait_for_ftp_service.php
   - docker exec -it ftpd_server sh -c "(echo test; echo test) | pure-pw useradd bob -f /etc/pure-ftpd/passwd/pureftpd.passwd -m -u ftpuser -d /home/ftpusers/bob"