Check for sails.io before checking for sails.io.httpServer

Handles edge case where the server has started initializing, but socket.io didn't get all the way there yet

lib/app/lower.js

@@ -79,7 +79,7 @@ module.exports = function lower(options, cb) {
         // the onClose event possibly being called multiple times (because you can't tell
         // socket.io to close without it trying to close the http server).  If we're piggybacking
         // we'll call sails.io.close in the main "shutdownHTTP" code below.
-        if (!_.isObject(sails.hooks) || !sails.hooks.sockets || (sails.io.httpServer && sails.hooks.http.server === sails.io.httpServer)) {
+        if (!_.isObject(sails.hooks) || !sails.hooks.sockets || (sails.io && sails.io.httpServer && sails.hooks.http.server === sails.io.httpServer)) {
           return cb();
         }