Checking in changes prior to tagging of version 0.18.

Changelog diff is:

diff --git a/Changes b/Changes
index e57496b..30018d5 100644
--- a/Changes
+++ b/Changes
@@ -2,6 +2,10 @@ Revision history for perl module Protocol::WebSocket

 {{$NEXT}}

+0.18 2014-09-01T14:45:16Z
+
+ - Digest::SHA1 -> Digest::SHA (Michal Špaček)
+
 0.17 2014-04-09T08:12:01Z

  - perl 5.8 unpack fix (Graham Ollis)