Improve modularity of jinja2 extensions

Change-Id: I86549a7a5002fa88008a4debfa4b5cf15a756c06
diff --git a/lib/xos-genx/MANIFEST.in b/lib/xos-genx/MANIFEST.in
index 3629bae..f6da5db 100644
--- a/lib/xos-genx/MANIFEST.in
+++ b/lib/xos-genx/MANIFEST.in
@@ -1 +1,2 @@
-include xosgenx/targets/*
\ No newline at end of file
+include xosgenx/targets/*
+include xosgenx/jinja2_extensions/*