[FIX] install pypdf to run odoo

.travis.yml

@@ -22,6 +22,7 @@ env:
 install: 
     - pip install coveralls flake8
     - pip install http://download.gna.org/pychart/PyChart-1.39.tar.gz
+    - pip install pypdf
     - pip install ${ODOO}
 
 # Create databae