Add docker tests to travis.yml

.travis.yml

@@ -5,6 +5,9 @@ branches:
     - master
 python:
   - "2.7"
+sudo: required
+services:
+  - docker
 install:
   - "sudo apt-get update -qq"
   - "sudo apt-get install -y nodejs python-demjson"
@@ -60,3 +63,5 @@ script:
     root_dir=$output_dir
     environment_deployments="."
     source $ROOT_DIR/tests/validate_templates.sh
+
+  - cd $TRAVIS_BUILD_DIR; make docker.test