start Xvfb properly

.travis.yml

@@ -97,11 +97,12 @@ install:
     elif [ "$BUILD" = "windows" ]; then
       set -x
 
+      sudo apt-get install xvfb
+      export DISPLAY=:99.0
+      Xvfb :99.0 &
+
       sudo add-apt-repository ppa:ubuntu-wine/ppa -y
       sudo apt-get update -qq
-      export DISPLAY=:99.0
-      sh -e /etc/init.d/xvfb start
-      sleep 3
       sudo apt-get -q install -y wine
 
       export WINEDEBUG=-all