Add v2ex plugin and another zhihu plugin

[V2EX](http://v2ex.com) is a developer community in china. I add a plugin to read latest topics on V2EX.

I know there's already one zhihu plugin which simply shows one webpage for zhihu daily.

I think maybe someone like me would prefer articles shown as search result list items, and then we can glance at all the titles, choose one we are interested and press enter to read it.