Release v6.1.4

[#107] 修改上传域名为upload.qiniu.com

Release v6.1.3

[#98] 增加pfop 功能
[#99] 增加针对七牛callback的检查

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