set jansson to 2.0

diff --git a/jansson b/jansson
index a5a43ca..279d8bf 160000 (submodule)
--- a/jansson
+++ b/jansson
@@ -1 +1 @@
-Subproject commit a5a43caa9a92a9c20a0b7ab6efce33106850895a
+Subproject commit 279d8bf108bd1367bdd3647e881146e1acf0123d