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/RedisCacheAdapter.spec.js

@@ -1,4 +1,4 @@
-const RedisCacheAdapter = require('../src/Adapters/Cache/RedisCacheAdapter').default;
+const RedisCacheAdapter = require('../lib/Adapters/Cache/RedisCacheAdapter').default;
 /*
 To run this test part of the complete suite
 set PARSE_SERVER_TEST_CACHE='redis'