Add stubs for postgresql setup and teardown

src/addons.js

@@ -35,6 +35,10 @@ var KNOWN_ADDONS = {
     mysql: {
         setup: setupMySql,
         teardown: teardownMySql
+    },
+    postgresql: {
+        setup: setupPostgreSql,
+        teardown: teardownPostgreSql
     }
 };
 
@@ -193,3 +197,11 @@ function teardownMySql(app, callback) {
     });
 }
 
+function setupPostgreSql(app, callback) {
+    return callback(null);
+}
+
+function teardownPostgreSql(app, callback) {
+    return callback(null);
+}
+