Checking in changes prior to tagging of version 0.12.

Changelog diff is:

diff --git a/Changes b/Changes
index 467d8e9..f0f738d 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,7 @@
 Revision history for Perl extension CGI::Header::PSGI.

+0.12  Apr 13th, 2013
+
   [BUG FIX]

     - Rename "cookie" to "cookies" in _as_arrayref()