Merge branch 'master' of https://github.com/ltsopensource/light-task-…

…scheduler

1.6.9 release

Merge pull request #290 from ltsopensource/develop

1.6.8

Merge pull request #281 from ltsopensource/develop

1.6.8-beta, 更新文档地址

Merge pull request #250 from ltsopensource/develop

1.6.6 release

1.6.5 release

Merge pull request #197 from qq254963746/develop

1.6.4 release

Merge pull request #167 from qq254963746/develop

1.6.3 release

Merge pull request #151 from qq254963746/develop

add mapdb FailStore and other upgrade