Truffle config file from https://github.com/ajb413/crowdsalable-eth-token.

truffle.js

const mnemonic = process.env.ethereum_mnemonic;
const HDWalletProvider = require("truffle-hdwallet-provider");

require('babel-register');
require('babel-polyfill');

module.exports = {
  build: "npm run dev",
  networks: {
    development: {
      host: "127.0.0.1",
      port: 9545,
      network_id: "*" // Match any network id
    },
    ropsten: {
      provider: new HDWalletProvider(mnemonic, "https://ropsten.infura.io/"),
      network_id: 3
    }
  }
};