Update to Truffle 4.1.5 and Ganache 6.1.0 (#876)

* Update to ganache-cli v6.1.0 and truffle v4.1.0

* Update to stable version of ganache-cli

* fix: update event emission warning

- Fix event emission warnings for solidity 4.21 after truffle has been
updated to use this version

* fix pr review comments

* update to truffle v4.1.5

* update package-lock

* add additional emit keywords

* update solidity-coverage to 0.4.15

* update to solium 1.1.6

* fix MerkleProof coverage analysis by testing through wrapper

* change version pragma to ^0.4.21

* fix solium linting errors

truffle.js

@@ -0,0 +1,43 @@
+require('dotenv').config();
+require('babel-register');
+require('babel-polyfill');
+
+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: {
+      host: 'localhost',
+      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
+      port: 8555,
+      gas: 0xfffffffffff,
+      gasPrice: 0x01,
+    },
+    ganache: {
+      host: 'localhost',
+      port: 8545,
+      network_id: '*', // eslint-disable-line camelcase
+    },
+  },
+};