从win8 开始，MS修改了文件和协议的关联方式，普通的注册表修改是无效的。
必须使用组策略(group policy )对象GP才行。
http://blogs.technet.com/b/mrmlcgn/archive/2013/02/26/windows-8-associate-a-file-type-or-protocol-with-a-specific-app-using-a-gpo-e-g-default-mail-client-for-mailto-protocol.aspx
https://technet.microsoft.com/en-us/library/hh825038.aspx
http://www.datazx.cn/Forums/en-US/0dec1d9d-f6bb-4c4c-926b-83acd2da985c/action
https://social.msdn.microsoft.com/Forums/windowsdesktop/zh-CN/0dec1d9d-f6bb-4c4c-926b-83acd2da985c/how-to-set-default-browser-in-windows-8-using-c?forum=windowscompatibility
http://itbbs.pconline.com.cn/soft/15143469.html
http://bbs.blueidea.com/thread-3089389-1-1.html