Use 'with' method rather than having to call close
Use 'with' method rather than having to call close

gzip.GzipFile() supports 'with' statement usage. Use that rather than
having to call close() explicitly. Plus with a 'with' statement if
there is an exception it will still call close()

Change-Id: I8535dffd66ffd7244b8bdcc4d79d6cf437a4d779

openstack/python-ironicclient,openstack/python-ironicclient