修改：     README.md

change "新手入门" to "线性回归"

	修改：     README.cn.md

Update package.json to fix security vulnerability

Update mirror registry server addr

add comment to mnist client.py

fix recognize_digits infer

fix the white space issue.

Update the fit_a_line/infer.py to use the uci_housing.model

Add quick start code

Update code

Website deploy scripts

fix a bug in saving model (invoke the wrong function).

* Fixes anchor issues, except for ch1.

* Remove old files.

Minor linking changes; clarity improvement

Updated content of the book