CDB-3079 tries to use cartodb flavour of postgres/postgis

.travis.yml

@@ -1,8 +1,9 @@
-addons:
-  postgresql: "9.3"
-
 before_script:
   - sudo apt-get install -q gdal-bin
+  - sudo apt-add-repository --yes ppa:cartodb/postgresql-9.3
+  - sudo apt-add-repository --yes ppa:cartodb/gis
+  - sudo apt-get update
+  - sudo apt-get install -q postgresql-9.3-postgis-2.1
   - psql -c 'create database template_postgis;' -U postgres
   - psql -c 'CREATE EXTENSION postgis;' -U postgres -d template_postgis
   - ./configure