Fix Mattermost info message

mattermost/mattermost.py

@@ -72,10 +72,10 @@ class MattermostCollector():
         # Get all instances stats
         for instance in self.instances:
             # Get current stats
-            print("Mattermost : collecting for instance {}".format(instance['name']))
+            print("Mattermost : collecting for instance {}".format(instance['config']['name']))
             data = self._get_stats(instance)
             if data is None:
-                print('Unable to get stats from Mattermost instance ' + instance['config']['url'])
+                print('Unable to get stats from Mattermost instance ' + instance['config']['name'])
                 continue
             # Get current miliseconds timestamp
             current_timestamp = int(datetime.datetime.now().timestamp()*1000)