fix: sniff for child.stdout before using it

This fixes node@6.0.0, but it's a hack, so I'm going to emit a message
saying that non-LTS is not supported.

lib/monitor/run.js

@@ -260,7 +260,12 @@ function run(options) {
       child.stdin.on('error', () => { });
       process.stdin.pipe(child.stdin);
     } else {
-      child.stdout.pipe(process.stdout);
+      if (child.stdout) {
+        child.stdout.pipe(process.stdout);
+      } else {
+        utils.log.error(`running an unsupported version of node ${process.version}`);
+        utils.log.error('nodemon may not work as expected - please consider upgrading to LTS');
+      }
     }
 
     bus.once('exit', function () {