Flush metrics once all metrics are generated

Fixes - Grok metrics can take minutes to show up on the server #50

grok_scraper.py

@@ -309,7 +309,7 @@ def print_metric(metric_name, timestamp, value, tags):
             utils.err("Unexpected error: %s" % sys.exc_info()[0])
             traceback.print_exc()
             die()
-
+    sys.stdout.flush()
 
 if __name__ == '__main__':
     main()