changelog [ci skip]

[ci skip]

Merge pull request qiniu#67 from qiniu/develop

Release 6.1.0

Merge pull request qiniu#61 from qiniu/develop

Release 6.0.5

Merge pull request qiniu#58 from qiniu/develop

Release 6.0.4

Merge pull request qiniu#49 from qiniu/develop

Release v6.0.3

Merge pull request qiniu#43 from qiniu/develop

Release 6.0.2

Merge pull request qiniu#40 from qiniu/develop

Release 6.0.1

Merge pull request qiniu#20 from qiniu/develop

Release v6.0.0

http client connpool