* #815 add S3 client

* #815 update S3 interface

* #815 add bucket_name_ as class field, add StartService() and StopService()

* #815 add FileIOReader and FileIOWriter

* #815 fix unittest test_storage build error

* #815 add GetObjectStr()

* #815 add S3IOReader/S3IOWriter

* #815 add ListObjects(), support put string with \0, launch S3 service when server start

* #815 read/write s3 index file pass

* #815 add MinIO related config

* #815 fix storage config issuegs

* #815 code clean

* #815 use local file or S3 via minio_enable

* #815 add DeleteObjects() for S3

* #815 print out IO rate when read_index & write_index

* #815 clean code

* #815 fix centos build error

* #815 support MinIO storage

* #815 fix typo