tools: update test-npm to work with npm 3

Refs: https://github.com/nodejs/node/pull/3308
PR-URL: https://github.com/nodejs/node/pull/3489
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

tools/test-npm.sh

@@ -29,10 +29,9 @@ export npm_config_prefix="$(pwd)/npm-prefix"
 export npm_config_tmp="$(pwd)/npm-tmp"
 
 # install npm devDependencies and run npm's tests
-
 ../$NODE cli.js install --ignore-scripts
-../$NODE cli.js run-script test-legacy
-../$NODE cli.js run-script test
+../$NODE test/run.js
+../$NODE cli.js run-script tap -- "test/tap/*.js"
 
 # clean up everything one single shot
 cd .. && rm -rf test-npm