CI testing for docker-compose build

refs. https://docs.travis-ci.com/user/docker/

Author: blooper05

.travis.yml

@@ -1,5 +1,22 @@
+sudo: required
+
 language: python
+
+services:
+  - docker
+
+env:
+  - DOCKER_COMPOSE_VERSION=1.21.1
+
+before_install:
+  - sudo rm /usr/local/bin/docker-compose
+  - curl -L https://github.com/docker/compose/releases/download/${DOCKER_COMPOSE_VERSION}/docker-compose-`uname -s`-`uname -m` > docker-compose
+  - chmod +x docker-compose
+  - sudo mv docker-compose /usr/local/bin
+
 install:
   - pip install -r requirements-dev.txt
+
 script:
   - bash tests/scripts/unit_tests.sh
+  - travis_wait docker-compose build