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/ParseWebSocket.spec.js

@@ -1,4 +1,4 @@
-const ParseWebSocket = require('../src/LiveQuery/ParseWebSocketServer').ParseWebSocket;
+const ParseWebSocket = require('../lib/LiveQuery/ParseWebSocketServer').ParseWebSocket;
 
 describe('ParseWebSocket', function() {