Use the app_info->name instead of the hostname

This makes more sense in case you run BCS, SGSN and other components
on the same host.  Having multiple telnet sessions with the same
prompt can otherwise be confusing.
diff --git a/src/vty/vty.c b/src/vty/vty.c
index 5c5a908..a5b16dc 100644
--- a/src/vty/vty.c
+++ b/src/vty/vty.c
@@ -306,7 +306,7 @@
 	const char *hostname;
 
 	if (vty->type == VTY_TERM) {
-		hostname = host.name;
+		hostname = host.app_info->name;
 		if (!hostname) {
 			uname(&names);
 			hostname = names.nodename;