Make idp settings optional

Author: pitbulk

src/onelogin/saml2/settings.py

@@ -201,7 +201,9 @@ def __load_settings_from_dict(self, settings):
         if len(errors) == 0:
             self.__errors = []
             self.__sp = settings['sp']
-            self.__idp = settings['idp']
+
+            if 'idp' in settings:
+                self.__idp = settings['idp']
 
             if 'strict' in settings:
                 self.__strict = settings['strict']