install xvfb

Author: ocefpaf

.travis.yml

@@ -2,6 +2,11 @@ language: minimal
 
 sudo: false
 
+addons:
+  apt:
+    packages:
+      - xvfb
+
 env:
   global:
     # Doctr deploy key for pyoceans/python-oceans
@@ -30,6 +35,7 @@ before_install:
   # GUI tests.
   - "export DISPLAY=:99.0"
   - "sh -e /etc/init.d/xvfb start"
+  — sleep 3
 
 install:
   # Test source distribution.