add build script

build.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+# Copyright (c) 2016-2020 The Hush developers
+# Distributed under the GPLv3 software license, see the accompanying
+# file COPYING or https://www.gnu.org/licenses/gpl-3.0.en.html
+
+set -eu -o pipefail
+cd cli
+cargo build --release