fix snap link and badge

Author: billzhong

README.md

@@ -1,6 +1,6 @@
 # shadowsocks-libev
 
-[![Build Status](https://travis-ci.com/shadowsocks/shadowsocks-libev.svg?branch=master)](https://travis-ci.com/shadowsocks/shadowsocks-libev) [![Snap Status](https://build.snapcraft.io/badge/shadowsocks/shadowsocks-libev.svg)](https://build.snapcraft.io/user/shadowsocks/shadowsocks-libev)
+[![Build Status](https://travis-ci.com/shadowsocks/shadowsocks-libev.svg?branch=master)](https://travis-ci.com/shadowsocks/shadowsocks-libev) [![Snap Status](https://snapcraft.io/shadowsocks-libev/badge.svg)](https://snapcraft.io/shadowsocks-libev)
 
 ## Intro