Updated Travis Docker version

.travis.yml

@@ -14,6 +14,12 @@ notifications:
 services:
 - docker
 
+before_install:
+  - curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+  - sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
+  - sudo apt-get update
+  - sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce
+
 # cache:
 #   directories:
 #   - docker_images