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/ParseWebSocketServer.spec.js

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