Add test nvm_install_with_node_version under test/install_script

test/install_script/nvm_install_with_node_version

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+die () { echo "$@" ; exit 1; }
+
+NODE_VERSION=8 \. ../../install.sh
+
+# nvm installed node 8
+(nvm ls | grep 8) > /dev/null 2>&1 || die "nvm didn't install node 8"