First of all, install nodejs, then:
npm install -g grunt grunt-cli
npm install
grunt
Open browser at the location specified in grunt output.
You can deploy to heroku this way:
# you may use a different name here:
heroku create littleexplorers-frontend --region eu
git push heroku master
After a ton of output, you will be able to connect to your web deployed app just typing the url prompted from git at execution end, in example:
http://littleexplorers-frontend.herokuapp.com