Add babel deps and configs, npm build script

.gitignore

@@ -59,3 +59,4 @@ build/Release
 # https://docs.npmjs.com/misc/faq#should-i-check-my-node-modules-folder-into-git
 node_modules
 
+dist

babel.config.js

@@ -0,0 +1,7 @@
+const presets = [
+  [
+    '@babel/env'
+  ]
+]
+
+module.exports = { presets }

package.json

@@ -2,15 +2,17 @@
   "name": "ethereumjs-blockchain",
   "version": "3.4.0",
   "description": "A module to store and interact with blocks",
-  "main": "index.js",
+  "main": "dist/index.js",
   "files": [
-    "*.js"
+    "dist/**/*.js"
   ],
   "scripts": {
+    "prepublishOnly": "npm run lint && npm run test && npm run build",
+    "build": "babel src --out-dir dist",
     "coverage": "nyc npm run test && nyc report --reporter=text-lcov > .nyc_output/lcov.info",
     "coveralls": "npm run coverage && coveralls <.nyc_output/lcov.info",
     "lint": "standard",
-    "test": "tape ./test/index.js"
+    "test": "tape ./test/*.js"
   },
   "repository": {
     "type": "git",
@@ -39,6 +41,9 @@
     "semaphore": "^1.1.0"
   },
   "devDependencies": {
+    "@babel/cli": "^7.2.3",
+    "@babel/core": "^7.2.2",
+    "@babel/preset-env": "^7.3.1",
     "coveralls": "^3.0.2",
     "nyc": "^13.0.1",
     "standard": "^11.0.1",

test/index.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const test = require('tape')
-const Blockchain = require('..')
+const Blockchain = require('../src')
 const Block = require('ethereumjs-block')
 const Common = require('ethereumjs-common').default
 const async = require('async')