use cross-spawn to spawn mocha in integration tests

package.json

@@ -325,6 +325,7 @@
     "browserify": "^13.0.0",
     "coffee-script": "^1.10.0",
     "coveralls": "^2.11.15",
+    "cross-spawn": "^5.1.0",
     "eslint": "^3.11.1",
     "eslint-config-semistandard": "^7.0.0",
     "eslint-config-standard": "^6.2.1",

test/integration/helpers.js

@@ -1,6 +1,6 @@
 'use strict';
 
-var spawn = require('child_process').spawn;
+var spawn = require('cross-spawn').spawn;
 var path = require('path');
 var baseReporter = require('../../lib/reporters/base');