Localization support

Localization support. Finnish language added as a second language for the system. Also fixed an issue that could have shown direct error messages to the end users.

Needs testing before merge

src/tjts5901/app.py

@@ -86,6 +86,12 @@ load_dotenv()
 app = create_app()
 
 
+# a simple page that says hello
+@flask_app.route('/hello')
+def hello():
+    return _('Hello, World!')
+
+
 @app.route("/server-info")
 def server_info() -> Response:
     """