Version 0.2.0

What's Changed

• Implement BucketIterator by @karajan1001 in #33
• add a new api get_object_meta by @karajan1001 in #34
• Add a new method object_exists. by @karajan1001 in #35
• add new api get_bucket_info by @karajan1001 in #36
• add new api append_object by @karajan1001 in #38
• add new api put_object_from_file by @karajan1001 in #39
• Add a new command get_object_to_file by @karajan1001 in #40
• Add a new command batch_delete_objects by @karajan1001 in #41
• add new api copy_object by @karajan1001 in #42

Full Changelog: 0.1.5...0.2.0