Make Truffle provider creation lazy (#1526)

* make provider creation lazy

* change getter for function

* remove unused networks from truffle config

* remove unused dotenv package

* remove truffle-hdwallet-provider dependency

* install ethereumjs-util

* replace sha3 with keccak256 for ethereumjs-util v6

truffle-config.js

@@ -1,19 +1,3 @@
-require('dotenv').config();
-
-const HDWalletProvider = require('truffle-hdwallet-provider');
-
-const providerWithMnemonic = (mnemonic, rpcEndpoint) =>
-  new HDWalletProvider(mnemonic, rpcEndpoint);
-
-const infuraProvider = network => providerWithMnemonic(
-  process.env.MNEMONIC || '',
-  `https://${network}.infura.io/${process.env.INFURA_API_KEY}`
-);
-
-const ropstenProvider = process.env.SOLIDITY_COVERAGE
-  ? undefined
-  : infuraProvider('ropsten');
-
 module.exports = {
   networks: {
     development: {
@@ -21,10 +5,6 @@ module.exports = {
       port: 8545,
       network_id: '*', // eslint-disable-line camelcase
     },
-    ropsten: {
-      provider: ropstenProvider,
-      network_id: 3, // eslint-disable-line camelcase
-    },
     coverage: {
       host: 'localhost',
       network_id: '*', // eslint-disable-line camelcase
@@ -32,10 +12,5 @@ module.exports = {
       gas: 0xfffffffffff,
       gasPrice: 0x01,
     },
-    ganache: {
-      host: 'localhost',
-      port: 8545,
-      network_id: '*', // eslint-disable-line camelcase
-    },
   },
 };