全球都在用的Gravatar头像接口，目前正常的几个Gravatar头像接口，最后一个是QQ头像接口。
http://fdn.geekzu.org/avatar/e23163bb2fc9da09505510cc1e5c02ee
https://sdn.geekzu.org/avatar/e23163bb2fc9da09505510cc1e5c02ee
http://cn.gravatar.com/avatar/e23163bb2fc9da09505510cc1e5c02ee
https://cdn.v2ex.com/gravatar/e23163bb2fc9da09505510cc1e5c02ee
https://dn-qiniu-avatar.qbox.me/avatar/e23163bb2fc9da09505510cc1e5c02ee
https://gravatar.loli.net/avatar/e23163bb2fc9da09505510cc1e5c02ee
http://q1.qlogo.cn/g?b=qq&nk=QQ号码&s=640