Release v6.1.2

Merge pull request #96 from qiniu/develop

Release v6.1.2

Release v6.1.1

Merge pull request #90 from qiniu/develop

Bug fix: check buffer

Release v6.1.0

Merge pull request #86 from qiniu/develop

Update package.json

Release v6.0.0

Merge pull request #72 from qiniu/develop

Release 6.0.0