Add a new dependency for n-api

msgpack-python is missing as a dependency in Ubuntu.

Fix Bug #1186739

Change-Id: I9e6ccc27970fb9fef2352a3d9864f325160a6e19
diff --git a/files/apts/n-api b/files/apts/n-api
index 0f08daa..e0e5e7f 100644
--- a/files/apts/n-api
+++ b/files/apts/n-api
@@ -1 +1,2 @@
 python-dateutil
+msgpack-python