ndnmap-data-collector: Update to ndn-cxx 0.5.1

Change-Id: Ie599d2eb34387282f929e452eca9b0852d8329d5
diff --git a/ndnmap-data-collector/Makefile b/ndnmap-data-collector/Makefile
index 3f4c3be..34d3ca6 100644
--- a/ndnmap-data-collector/Makefile
+++ b/ndnmap-data-collector/Makefile
@@ -11,6 +11,6 @@
 VERSION=0.1.0-3-g66d2a5
 
 # PPA version
-PPA_VERSION=1
+PPA_VERSION=2
 
 include ../packaging.mk