CI test py(2.7, 3.{5-7})

Author: rasmunk

.travis.yml

@@ -1,7 +1,12 @@
+dist: xenial
 sudo: required
 services: docker
 language: python
-python: '3.6'
+python:
+- '2.7'
+- '3.5'
+- '3.6'
+- '3.7'
 before_install:
 - sudo apt-get update
 - sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce