Fix up this-and-that

package.json

@@ -8,6 +8,9 @@
     "prepublish": "npm run compile",
     "test": "npm run compile && mocha test-dist/*"
   },
+  "bin": {
+    "electron-rebuild": "lib/cli.js"
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/paulcbetts/electron-rebuild"
@@ -27,6 +30,7 @@
     "ncp": "^2.0.0",
     "npm": "^2.9.0",
     "promise": "^7.0.1",
-    "rimraf": "^2.3.3"
+    "rimraf": "^2.3.3",
+    "yargs": "^3.8.0"
   }
 }

src/main.js

@@ -1,4 +1,4 @@
-require('babel-core');
+require('babel/polyfill');
 
 import path from 'path';
 import _ from 'lodash';
@@ -56,7 +56,7 @@ export async function installNodeHeaders(nodeVersion, nodeDistUrl=null, headersD
   await spawnWithHeadersDir(cmd, args, headersDir);
 }
 
-export async function rebuildNativeModules(nodeVersion, nodeModulesPath=null, headersDir=null) {
+export async function rebuildNativeModules(nodeVersion, nodeModulesPath, headersDir=null) {
   headersDir = headersDir || getHeadersRootDirForVersion(nodeVersion);
   await checkForInstalledHeaders(nodeVersion, headersDir);