For Grunt you need to commit also the packages.json file.
To start working with Grunt, instal the CLI:
$ sudo npm install -g grunt-cli
More info here.
To install Grunt, you need to install NPM (Node JS Package Manager) and NodeJS:
$ sudo aptitude install npm $ sudo aptitude install nodejs-legacy
To install Grunt for a specific project I had to execute the following:
$ sudo npm install grunt --save-dev
If some modules were not installed you need to install it for the local project:
$ sudo npm install -g grunt-contrib-uglify
$ sudo npm install -g grunt-contrib-clean
$ sudo npm install -g grunt-contrib-copy
I had to install project dependencies:
$ npm install
It is probably advisable to commit bower_components together with the project. It contains .bower.json files which contains which modules are installed and from where.