feat: enable overrideMethod middleware by default

[fengmk2]

only allow override method on POST request by default

#324

Checklist

• npm test passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

Description of change

[mention-bot]

@fengmk2, thanks for your PR! By analyzing the history of the files in this pull request, we identified @popomore, @dead-horse and @shaoshuai0102 to be potential reviewers.

[fengmk2]

依赖 eggjs/koa-override#3 合并发布

[fengmk2]

appveyor 只是 report 问题，test 是过的

[dead-horse]

windows 下挂了？

[dead-horse]

合并了

[fengmk2]

我提个release pr

[fengmk2]

跟 #1027 一起合并再发版本。