async/await not supported

[zypA13510]

Issue description: when using async/await keyword in code, atom-npm-install will prompt "Unexpected token" and refuse to process the dependencies in the file.

Steps to reproduce:

1. Create a new project folder and run npm init with default settings;
2. Create a new file in the created folder, and name it to index.js;
3. Paste the following code into index.js:

var express = require('express');

async function main() {
  var a = new Promise(
    (resolve, reject) => {
      setTimeout(resolve, 1000, 'Hello World!');
    }
  );
  console.log(a);
  console.log(await a);
  return a;
}

main();

4. Save the file and run Npm Install: Save from Atom command palette.

Expected result: express installed and added to package.json Actual result: A new panel opened in Atom that says npm install 3: Unexpected token (3:6)

Environment: Atom 1.25.1 x64 npm-install 4.0.4

[krainboltgreene]

Same with flowtype.