Prepare 0.6.0 release

Change-Id: I4cea28b09b20f5359f0e2ddaf188b234b2b102f9
Refs: #4275
diff --git a/wscript b/wscript
index af0748b..bcfe928 100644
--- a/wscript
+++ b/wscript
@@ -3,7 +3,7 @@
 from waflib import Logs, Utils, Context
 import os
 
-VERSION = "0.5.1"
+VERSION = "0.6.0"
 APPNAME = "ndn-cxx"
 PACKAGE_BUGREPORT = "https://redmine.named-data.net/projects/ndn-cxx"
 PACKAGE_URL = "http://named-data.net/doc/ndn-cxx/"