Update WebSocket++ to 0.8.1

Change-Id: I185c26a78aaf8ba6edeec935b0b0e3aa6c6c5f4c
diff --git a/COPYING.md b/COPYING.md
index ba181d9..dff0546 100644
--- a/COPYING.md
+++ b/COPYING.md
@@ -11,7 +11,7 @@
 - SQLite is in [public domain](http://www.sqlite.org/copyright.html)
 
 - WebSocket++ library licensed under conditions of
-  [BSD license](https://github.com/zaphoyd/websocketpp/blob/0.7.0/COPYING)
+  [BSD license](https://github.com/zaphoyd/websocketpp/blob/0.8.1/COPYING)
 
 - Libpcap library licensed under conditions of
   [a 3-clause BSD license](http://www.tcpdump.org/license.html).