Merge pull request #16 from qiniu/develop

Release v6.0.0
Merge pull request #32 from qiniu/develop

merge to master
Merge pull request #33 from qiniu/develop

Update CHANGELOG.md
Merge pull request #42 from qiniu/develop

doc.qiniu.com release 6.1.2
fix link to audio/video
Merge pull request #43 from longshanksmo/fix/sdk-link

fix link to audio/video
hot fix menu style
Merge pull request #45 from icattlecoder/hotfix_menustyle

Hotfix menustyle
Update CHANGELOG.md
Update CHANGELOG.md