Use postgresql for travis

app/config/config_travis.yml

@@ -0,0 +1,28 @@
+imports:
+    - { resource: config_dev.yml }
+
+framework:
+    test: ~
+    session:
+        storage_id: session.storage.mock_file
+    profiler:
+        collect: false
+
+web_profiler:
+    toolbar: false
+    intercept_redirects: false
+
+swiftmailer:
+    disable_delivery: true
+
+liip_functional_test: ~
+
+doctrine:
+    dbal:
+        driver:   "pdo_pgsql"
+        host:     "localhost"
+        port:     "5432"
+        dbname:   "travis_ci_test"
+        user:     "postgres"
+        password: ""
+        charset:  UTF8