Improve test coverage

Author: LKaemmerling

.travis.yml

@@ -4,7 +4,7 @@ before_script:
   - composer global require hirak/prestissimo
   - composer install
   - docker pull lkdevelopment/hetzner-cloud-api-mock
-  - docker run -d -p 127.0.0.1:4000:8080 lkdevelopment/hetzner-cloud-api-mock
+  - docker run -d -p 127.0.0.1:8080:8080 lkdevelopment/hetzner-cloud-api-mock
   - docker ps -a
   - sleep 2
   # list any PHP version you want to test against