add acceptance tests on debian 9

Author: bastelfreak

.sync.yml

@@ -2,4 +2,5 @@
 .travis.yml:
   docker_sets:
     - set: docker/centos-7
+    - set: docker/debian-9
   secure: "l2HEhssQyDQGrdBkGS8f/gQ4FA5vVLM0JegyAVaaIXpRrJYgRiDAvC+u81HS//+J0v9cr4jo74ncl1HGU0QJZURJX/L8DJqUVXzSZpe9HmfrQpV1RDUSNMqzaIq5Z268Ou9n1Jkeg58WJyIaks9PQhXoWRRSnaCyDHrbGM8XcAU="

.travis.yml

@@ -31,6 +31,12 @@ matrix:
     env: PUPPET_INSTALL_TYPE=agent BEAKER_debug=true BEAKER_set=docker/centos-7 CHECK=beaker
     services: docker
     sudo: required
+  - rvm: 2.4.3
+    bundler_args: --without development release
+    dist: trusty
+    env: PUPPET_INSTALL_TYPE=agent BEAKER_debug=true BEAKER_set=docker/debian-9 CHECK=beaker
+    services: docker
+    sudo: required
 branches:
   only:
   - master