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/WinstonLoggerAdapter.spec.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const WinstonLoggerAdapter = require('../src/Adapters/Logger/WinstonLoggerAdapter').WinstonLoggerAdapter;
+const WinstonLoggerAdapter = require('../lib/Adapters/Logger/WinstonLoggerAdapter').WinstonLoggerAdapter;
 const request = require('request');
 
 describe('info logs', () => {