Checking in changes prior to tagging of version v1.6.0.

Changelog diff is:

diff --git a/Changes b/Changes
index aec90cd..1714a59 100644
--- a/Changes
+++ b/Changes
@@ -2,6 +2,11 @@ Revision history for Perl extension App::plenv

 {{$NEXT}}

+v1.6.0 2013-05-26T10:32:21Z
+
+    - uninstall command
+      (Shoichi Kaji)
+
 1.5.0 2013-05-17T02:14:45Z

     - ~/.plenv/build/ as a default building directory. And do not remove building directory by default