Fix apt commands

Author: gortazar

.travis.yml

@@ -2,9 +2,9 @@ dist: trusty
 sudo: required
 
 before_install:
-  - sudo add-apt-repository ppa:openjdk-r/ppa
+  - sudo add-apt-repository -y ppa:openjdk-r/ppa
   - sudo apt-get update
-  - sudo apt-get install openjdk-8-jdk
+  - sudo apt-get install -y openjdk-8-jdk
 
 language: java