Removes need to use babel-register (#4865)

* Removes need to use babel-register

- Adds watch to watch changes when running the test to regenerate
- Tests are now pure node 8

* Adds timing to helper.js

* Update contribution guide

* Adds inline sourcemaps generation to restore coverage

* nits

spec/ParseUser.spec.js

@@ -7,10 +7,10 @@
 
 "use strict";
 
-import MongoStorageAdapter from '../src/Adapters/Storage/Mongo/MongoStorageAdapter';
+const MongoStorageAdapter = require('../lib/Adapters/Storage/Mongo/MongoStorageAdapter').default;
 const request = require('request');
-const passwordCrypto = require('../src/password');
-const Config = require('../src/Config');
+const passwordCrypto = require('../lib/password');
+const Config = require('../lib/Config');
 const rp = require('request-promise');
 
 function verifyACL(user) {