新增4个爬虫

CST	Cell Signaling Technology	http://www.cellsignal.com
Cayman		http://www.caymanchem.com/
Anbo Biotech		http://www.anbobio.com/
AMRESCO		http://www.amresco-inc.com
修改采购清单细节

调整生成excel文件细节
爬虫分文件
Merge branch 'fanshaorui-master'

Conflicts:
	regeant/spiders/sigmaaldrich.py
	search_demo/templates/.DS_Store
合并爬虫代码