Update xvfb.

Author: khatchad

.travis.yml

@@ -5,9 +5,8 @@ cache:
     apt: true
     directories:
         - $HOME/.m2
+services:
+    - xvfb
 script: mvn clean verify -Pjacoco coveralls:report
-before_install:
-  - "export DISPLAY=:99.0"
-  - "sh -e /etc/init.d/xvfb start"
 notifications:
     slack: cunyponder:A8GuEoj0voEn2H7MJDL1eNji