Update getDefaultSchema

Author: loay

lib/discovery.js

@@ -331,6 +331,10 @@ function mixinDiscovery(PostgreSQL) {
   };
 
   PostgreSQL.prototype.getDefaultSchema = function() {
-    return '';
+    if (this.dataSource && this.dataSource.settings &&
+    this.dataSource.settings.database) {
+      return this.dataSource.settings.database;
+    }
+    return undefined;
   };
 }