Fixes #3547: Added locale de_DE

[tkempken]

I've added locale de_DE. Please see related pull requests in

react-component/m-calendar#107
react-component/m-date-picker#299

Thanks!

First of all, thank you for your contribution! :-)

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if isBugFix :

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elif isNewFeature :

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This change is 

[awmleer]

v2 已经不再维护了，这个 PR 先关闭了哈，如果有兴趣的话可以关注一下最新的 v5 版本～