Add caddy, a web server

At request of mholt/caddy#45

README.md

@@ -534,6 +534,7 @@ Join us on IRC at **#awesome-go** on freenode [web access](http://webchat.freeno
 ## Server Applications
 
 * [algernon](https://github.com/xyproto/algernon) - HTTP/2 web server with built-in support for Lua, Markdown, GCSS and Amber.
+* [Caddy](https://github.com/mholt/caddy) - Caddy is an alternative, HTTP/2 web server that's easy to configure and use.
 * [etcd](https://github.com/coreos/etcd) - A highly-available key value store for shared configuration and service discovery.
 * [nsq](http://nsq.io/) - A realtime distributed messaging platform