feat(spawn): support for quoted scripts

Use the shell option of spawn introduced in Node.js 4.8 (see
nodejs/node#4598) to pass the command to the OS shell.
Supersedes #77.

BREAKING CHANGE: Changes the behavior when passed quoted scripts or special characters interpreted
by the shell.

package.json

@@ -7,7 +7,7 @@
     "cross-env": "dist/bin/cross-env.js"
   },
   "engines": {
-    "node": ">=4.0"
+    "node": ">=4.8"
   },
   "scripts": {
     "start": "nps",

src/index.js

@@ -8,7 +8,11 @@ const envSetterRegex = /(\w+)=('(.+)'|"(.+)"|(.+))/
 function crossEnv(args) {
   const [command, commandArgs, env] = getCommandArgsAndEnvVars(args)
   if (command) {
-    const proc = spawn(command, commandArgs, {stdio: 'inherit', env})
+    const proc = spawn(command, commandArgs, {
+      stdio: 'inherit',
+      shell: true,
+      env,
+    })
     process.on('SIGTERM', () => proc.kill('SIGTERM'))
     process.on('SIGINT', () => proc.kill('SIGINT'))
     process.on('SIGBREAK', () => proc.kill('SIGBREAK'))

src/index.test.js

@@ -80,6 +80,7 @@ function testEnvSetting(expected, ...envSettings) {
   expect(crossSpawnMock.spawn).toHaveBeenCalledTimes(1)
   expect(crossSpawnMock.spawn).toHaveBeenCalledWith('echo', ['hello world'], {
     stdio: 'inherit',
+    shell: true,
     env: Object.assign({}, process.env, env),
   })