Checking in changes prior to tagging of version 0.12.

Changelog diff is:

diff --git a/Changes b/Changes
index 5459067..776e331 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,8 @@
 Revision history for Perl extension Plack::Middleware::Deflater

+0.12  Thu Sep 12 11:31:07 JST 2013
+        - add plack.skip-deflater flag for skip all Deflater features
+
 0.11  Tue Aug 6 23:24:07 JST 2013
         - fix bug around crc calculation and footer generation. Thanks syohex-san