Prepare release 0.6.0

Change-Id: I0a80e05ddf5e3b98544bf56575e13efae22ccb5b
Refs: #4275
diff --git a/wscript b/wscript
index 873b3c4..ffa6052 100644
--- a/wscript
+++ b/wscript
@@ -24,7 +24,7 @@
 NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-VERSION = "0.5.1"
+VERSION = "0.6.0"
 APPNAME = "nfd"
 BUGREPORT = "https://redmine.named-data.net/projects/nfd"
 URL = "https://named-data.net/doc/NFD/"