build: Update version number to 0.3.1

Change-Id: Ibbb64815f3d334c830bee734928813bbf99308bf
Refs: #2588
diff --git a/wscript b/wscript
index 01d69a7..abc0435 100644
--- a/wscript
+++ b/wscript
@@ -23,7 +23,7 @@
 NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-VERSION = "0.3.0"
+VERSION = "0.3.1"
 APPNAME = "nfd"
 BUGREPORT = "http://redmine.named-data.net/projects/nfd"
 URL = "http://named-data.net/doc/NFD/"