Error running Grunt Build on Heroku - node.js

Question

So I am installing a simple Backbone application on Heroku that I generated using the Yeoman Backbone generator. I have a very simple node.js server file to serve up the Backbone application, but had trouble deploying to Heroku due to missing dependencies:
Output:
remote: Loading "Gruntfile.js" tasks...ERROR
remote: >> Error: Cannot find module 'connect-livereload'
remote: Warning: Task "build" not found. Use --force to continue.
Server.js
var express = require('express');
var app = express();
var port = process.env.PORT || 8080;
app.use(express.static(__dirname + '/app'));
app.listen(port, function() {
console.log('App is running on port ' + port);
});
packages.json
{
"name": "ssi",
"version": "0.0.0",
"dependencies": {
...
},
"devDependencies": {
"bower": "^1.4.1",
"connect": "^3.3.5",
"grunt": "^0.4.5",
"grunt-cli": "^0.1.13",
...
},
"engines": {
"node": ">=0.10.0"
},
"scripts": {
"start": "node server.js",
"test": "mocha",
"postinstall": "bower install && grunt build"
}
}
Originally I had problems running bower install because I hadn't added bower to the dependencies in packages.json, so I thought, "maybe I have to add it to the normal dependencies list instead of devDependencies, since this is my deployment process.
So I added bower and grunt to the dependencies list, but then it would fail while running grunt build because now it couldn't find any of the required grunt modules used during the build task. I figured there must be a better way to let Heroku see these dependencies without adding them to the production dependencies list.
I already tried setting the NODE_ENV variable to "development" like so:
$ heroku config:set NODE_ENV=development
But that didn't seem to have any effect. So since I am answering my own question, the hypothetical question in question is:
"How do I get Heroku to run bower install and grunt build without having to move all my dependencies into the production dependencies list?"
N.B. - I realise that a "proper" deployment process might instead add all this stuff to a distribution folder, including the dependencies. This question and answer are aimed at those, like me, who are instead attempting to just push their current build to Heroku without having to set up a "better" deployment process just yet.

Answer 1

In the end the solution was very simple. In the first few lines of the console output when pushing my app to Heroku, is the following line:
remote: NPM_CONFIG_PRODUCTION=true
It appears that changing this environment variable to false will cause NPM to install the devDependencies list as well. So just type in the following:
$ heroku config:set NPM_CONFIG_PRODUCTION=false
And you should then see Heroku build and deploy successfully.