nfd: Update to version 0.5.1

Change-Id: I18270180692f0b70ab7c08d2f929e5815ab9493b
diff --git a/nfd/debian/nfd-status-http-server.service b/nfd/debian/nfd-status-http-server.service
index 3088a83..1ad2d56 100644
--- a/nfd/debian/nfd-status-http-server.service
+++ b/nfd/debian/nfd-status-http-server.service
@@ -28,6 +28,7 @@
 After=nfd.service
 
 [Service]
+Environment=HOME=/var/lib/ndn/nfd-status-http-server
 EnvironmentFile=-/etc/default/nfd-status-http-server
 ExecStart=/usr/bin/nfd-status-http-server $FLAGS
 Restart=on-failure