add join_settings

src/configuration/join_settings.py

+def join_settings(sampling="daily"):
+    if sampling == "daily":  # pragma: no branch
+        TOAR_SERVICE_URL = 'https://join.fz-juelich.de/services/rest/surfacedata/'
+        headers = {}
+    elif sampling == "hourly":
+        TOAR_SERVICE_URL = 'https://join.fz-juelich.de/services/rest/surfacedata/'
+        headers = {}
+    else:
+        raise NameError(f"Given sampling {sampling} is not supported, choose from either daily or hourly sampling.")
+    return TOAR_SERVICE_URL, headers