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/Subscription.spec.js

@@ -1,9 +1,9 @@
-const Subscription = require('../src/LiveQuery/Subscription').Subscription;
+const Subscription = require('../lib/LiveQuery/Subscription').Subscription;
 let logger;
 describe('Subscription', function() {
 
   beforeEach(function() {
-    logger = require('../src/logger').logger;
+    logger = require('../lib/logger').logger;
     spyOn(logger, 'error').and.callThrough();
   });