[FIX] Change travis configuration to download wkhtmltopdf last version

.travis.yml

@@ -3,17 +3,9 @@ cache: pip
 
 addons:
   apt:
-    sources:
-      - pov-wkhtmltopdf
     packages:
       - expect-dev  # provides unbuffer utility
       - python-lxml # because pip installation is slow
-      - wkhtmltopdf  # only add if needed and check the before_install section below
-
-# set up an X server to run wkhtmltopdf.
-before_install:
-  - "export DISPLAY=:99.0"
-  - "sh -e /etc/init.d/xvfb start"
 
 language: python
 
@@ -37,6 +29,7 @@ virtualenv:
 install:
   - git clone --depth=1 https://github.com/OCA/maintainer-quality-tools.git ${HOME}/maintainer-quality-tools
   - export PATH=${HOME}/maintainer-quality-tools/travis:${PATH}
+  - export WKHTMLTOPDF_VERSION=0.12.4
   - travis_install_nightly
 
 script: