Add captcha package

Author: TimothyYe

web.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/dchest/captcha"
 	"github.com/go-martini/martini"
 	"github.com/timothyye/vim-tips-web/routers"
 	"net/http"
@@ -15,6 +16,7 @@ func main() {
 	routers.Initialize(m)
 
 	http.HandleFunc("/ws", routers.WSHandler)
+	http.Handle("/captcha", captcha.Server(captcha.StdWidth, captcha.StdHeight))
 	http.Handle("/", m)
 
 	fmt.Println("Server started...")