travis add docker

Author: jvmlet

.travis.yml

@@ -9,6 +9,8 @@ cache:
   directories:
     - $HOME/.gradle/caches/
     - $HOME/.gradle/wrapper/
+services:
+  - docker
 before_install:
   - chmod +x ./publish.sh
   - "openssl aes-256-cbc -K $encrypted_12c8071d2874_key -iv $encrypted_12c8071d2874_iv -in codesigning.asc.enc -out codesigning.asc -d && gpg --import ./codesigning.asc || echo"