Checking in changes prior to tagging of version 0.20.

Changelog diff is:

diff --git a/Changes b/Changes
index bfc126e..050edb0 100644
--- a/Changes
+++ b/Changes
@@ -2,6 +2,9 @@ Revision history for Perl extension Growl::GNTP

 {{$NEXT}}

+0.20 2013-04-07T11:30:09Z
+        - depend on IO::Socket::PortState.
+
 0.19 2013-04-07T11:25:12Z
         - depend on IO::Socket::PortState.