add pinyin tool

add pinyin tool
Merge pull request #1 from CarlHwang/master

add pinyin tool
version_0.1
exit directory Docs to data
reorganize the structure
Ranking Code

BM25 Ranking Algorithm Template, need to implement the blank method
Merge pull request #2 from CarlHwang/master

Ranking Code
Merge pull request #1 from niyikai/master

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