Checking in changes prior to tagging of version 0.13.

Changelog diff is:

diff --git a/Changes b/Changes
index 4a5f86f..2a8da6f 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,11 @@
 Revision history for Perl extension Ukigumo::Client

+0.13    Wed Mar  6 11:32:13 2013
+    - Notify::Callback
+    - Executor::Command
+    - add `skip_if_unmodified` option to Role::VC and ukigumo-client.pl
+    - add `command` option to ukigumo-client.pl
+
 0.12

     - skip notification if $status is success and last status was skipped.