fix postgresql problem

Author: alesanchezr

src/app.py

@@ -18,8 +18,9 @@
 app.url_map.strict_slashes = False
 
 # database condiguration
-if os.getenv("DATABASE_URL") is not None:
-    app.config['SQLALCHEMY_DATABASE_URI'] = os.environ.get('DATABASE_URL')
+db_url = os.getenv("DATABASE_URL")
+if db_url is not None:
+    app.config['SQLALCHEMY_DATABASE_URI'] = db_url.replace("postgres://", "postgresql://")
 else:
     app.config['SQLALCHEMY_DATABASE_URI'] = "sqlite:////tmp/test.db"