Merge pull request #22 from psykzz/patch-1

travis.yml consistancies

Author: zopanix

.travis.yml

@@ -2,12 +2,12 @@ services: docker
 before_install:
   # set env vars in the build settings to interact with repositories
   # see https://docs.travis-ci.com/user/environment-variables/#Defining-Variables-in-Repository-Settings
-  - docker login -e="$DOCKER_EMAIL" -u="$DOCKER_USERNAME" -p="$DOCKER_PASSWORD"
+  - docker login -e="${DOCKER_EMAIL}" -u="${DOCKER_USERNAME}" -p="${DOCKER_PASSWORD}"
 script:
   - docker build -t "zopanix/factorio:${TRAVIS_TAG}" .
 deploy:
   provider: script
   script: docker push "zopanix/factorio:${TRAVIS_TAG}"
   skip_cleanup: false
   on:
-    tags: true
+    tags: true