Merge branch 'release/0.12.15' into develop
Impl bucket ACL basic APIs
Impl bucket ACL APIs for predefined users
Initialize acl values
Init ACL to private when creating at first
Change I/F to process records by a bucket
done UT
Add created_at field into bucket record to use in leo_gateway
Make sync_interval configurable
Upgrade leo_commons to v0.14.8
Bump leo_s3_libs to 0.12.16
Merge branch 'release/0.12.16'