MAC版本：EI Captain
Python版本: 2.7.10
MAC默认没有安装pip，所以首先
sudo easy_install pip
然后安装Scrapy:
sudo pip install Scrapy
安装过程中报错: "libxml/xmlversion.h' file not found"，解决方案如下:
brew install libxml2 brew install libxslt brew link libxml2 --force brew link libxslt --force
再次安装，成功。
然而，后续执行scrapy startproject tutorial命令，又报错了: "cannot import name xmlrpc_client"，我简直要疯了。解决方案如下:
sudo rm -rf /Library/Python/2.7/site-packages/six* sudo rm -rf /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/six* sudo pip install six
然而，执行scrapy startproject tutorial命令，再次报错: 'module' object has no attribute 'OP_NO_TLSv1_1'，解决方案如下:
sudo pip install Twisted==16.4.1
参考资料：
http://stackoverflow.com/questions/19548011/cannot-install-lxml-on-mac-os-x-10-9