add Knowledge Base delete and file delete

* 添加加命令行工具

* 添加加命令行工具

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Co-authored-by: zqt <1178747941@qq.com>
Co-authored-by: imClumsyPanda <littlepanda0716@gmail.com>

更改目前流式对话的传入模式，使其可以支持多轮对话，体现在新增参数：history、knowledge_base_id

fixed bug of upload file use fixed url

* jpg and png ocr

* fix

* write docs to tmp file

* fix

* image loader

* fix

* fix

* add pdf_loader

* fix

* update INSTALL.md

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Co-authored-by: imClumsyPanda <littlepanda0716@gmail.com>

* jpg and png ocr

* fix

* write docs to tmp file

* fix

* [BUGFIX] local_doc_qa.py line 172: logging have no end args. (#323)

* image loader

* fix

* fix

* update api.py

* update api.py

* update api.py

* update README.md

* update api.py

* add pdf_loader

* fix

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Co-authored-by: RainGather <3255329+RainGather@users.noreply.github.com>
Co-authored-by: imClumsyPanda <littlepanda0716@gmail.com>