Force the buffer to flush after each print

The info of print() is first output to the buffer and will not be printed
if the buffer is not full.
Use flush() to force the  buffer to flush after each print

Change-Id: I548962fb43043e4b9991892d354aed192aebf7c1

freezer/main.py

@@ -175,7 +175,9 @@ def run_job(conf, storage):
         pp.field_names = response[0]
         for i in response[1]:
             pp.add_row(i)
-        print(pp)
+        sys.stdout.writelines(pp.get_string())
+        sys.stdout.write('\n')
+        sys.stdout.flush()
     else:
         return