libpsync: add PSync and update NLSR dependency

refs: #4827

Change-Id: I83df4c0532258f490b855335bf94600cc71d7a65
diff --git a/libpsync/debian/source/format b/libpsync/debian/source/format
new file mode 100644
index 0000000..163aaf8
--- /dev/null
+++ b/libpsync/debian/source/format
@@ -0,0 +1 @@
+3.0 (quilt)