nfd: Update to version 0.5.1

Change-Id: I18270180692f0b70ab7c08d2f929e5815ab9493b
diff --git a/nfd/Makefile b/nfd/Makefile
index ef811f9..35ed35f 100644
--- a/nfd/Makefile
+++ b/nfd/Makefile
@@ -2,15 +2,15 @@
 GIT_URL=https://github.com/named-data/NFD.git
 
 # Tag name or commit hash for checkout
-GIT_VERSION=NFD-0.5.0
+GIT_VERSION=NFD-0.5.1
 
 # Package name
 NAME=nfd
 
 # Package version
-VERSION=0.5.0
+VERSION=0.5.1
 
 # PPA version
-PPA_VERSION=1
+PPA_VERSION=2
 
 include ../packaging.mk