Remove redundant shutil import

Author: Pawel Rozlach

kazoo/testing/common.py

@@ -244,7 +244,6 @@ def stop(self):
     def destroy(self):
         """Stop the ZooKeeper instance and destroy its on disk-state"""
         # called by at exit handler, reimport to avoid cleanup race.
-        import shutil
         self.stop()
 
         shutil.rmtree(self.working_path, True)