Uc query hosts order (qiniu#586)

changelog

Merge pull request qiniu#574 from YangSen-qn/master

version to v7.13.0

Merge pull request qiniu#570 from YangSen-qn/master

version to 7.12.1

Merge pull request qiniu#561 from YangSen-qn/resume-check-ctx-expire

Resume check ctx expire

Update README.md

ver up

Update Constants.java

up ver

Update Constants.java