Merge pull request qiniu#160 from fengyhack/master

v7.2.15 修复“生成时间戳防盗链”错误，弱化Json.NET依赖

Merge pull request qiniu#158 from fengyhack/master

版本更新v7.2.14

Merge pull request qiniu#154 from fengyhack/master

新增LabMD5，修复UnixTimestamp计算的问题

Merge pull request qiniu#150 from fengyhack/master

版本更新v7.2.11，新增MSTest for UWP

Merge pull request qiniu#146 from fengyhack/master

版本更新v7.2.9 新增单元测试

Merge pull request qiniu#141 from fengyhack/master

版本更新v7.2.8，修复一个已知问题

Merge pull request qiniu#136 from fengyhack/master

版本更新v7.2.7：新增UWP支持，新增async支持

Merge pull request qiniu#130 from fengyhack/master

版本更新v7.2.6 修复部分已知问题

Merge pull request qiniu#122 from fengyhack/master

版本更新v7.2.4 部分细节优化与错误修正

Merge pull request qiniu#118 from fengyhack/master

重写版本，更新至v7.2.2