Stop postgresql default instance

Stop travis postgres default instance before trying to install postgres
9.5.

.travis.yml

@@ -21,6 +21,7 @@ before_install:
   - sudo apt-get -y --no-install-recommends install python-scikits-learn=0.14.1-3-cdb2
 
   # Install postgres db and build deps
+  - sudo /etc/init.d/postgresql stop # stop travis default instance
   - sudo apt-get -y install postgresql-9.5 postgresql-server-dev-9.5 postgresql-plpython-9.5 postgresql-9.5-postgis-2.2 postgresql-9.5-postgis-scripts
 
   # configure it to accept local connections from postgres