hnbgw vty: add empty hnbgw and hnbgw/iuh vty nodes

Add include/osmocom/iuh/ named after this project (osmo-iuh), and add vty.h to
define VTY node enum values. Also add (to) Makefile.am and configure.ac to
include in the build.

An upcoming commit will add the actual first config item to the hnbgw/iuh node.

Change-Id: I71545823d3bd81cb888c85df8e298a56c98bf131
diff --git a/configure.ac b/configure.ac
index fc8c737..38e3b4c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,4 +41,5 @@
 	include/osmocom/hnbap/Makefile
 	include/osmocom/ranap/Makefile
 	include/osmocom/rua/Makefile
+	include/osmocom/iuh/Makefile
 	)