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/UserController.spec.js

@@ -1,6 +1,6 @@
-const UserController = require('../src/Controllers/UserController').UserController;
+const UserController = require('../lib/Controllers/UserController').UserController;
 const emailAdapter = require('./MockEmailAdapter')
-const AppCache = require('../src/cache').AppCache;
+const AppCache = require('../lib/cache').AppCache;
 
 describe('UserController', () => {
   const user = {