Refactor pushStatusHandler to use Parse instead of direct access (#4173)

* Refactors pushStatusHandler to use HTTP interface so we can bind CloudCode hooks

* Handle correctly nested dot atomic operations

* Better handling of restricted class names, add support for afterSave _PushStatus

* Adds simple testing for afterSave(PushStatus)

* Reverts jobStatusHandler

* Addresses fixes

* adds delays to all methods

spec/Parse.Push.spec.js

@@ -127,6 +127,7 @@ describe('Parse.Push', () => {
           alert: 'Hello world!'
         }
       }, {useMasterKey: true}))
+      .then(() => delayPromise(500))
       .then(() => {
         request.get({
           url: 'http://localhost:8378/1/classes/_PushStatus',
@@ -155,6 +156,7 @@ describe('Parse.Push', () => {
           alert: 'Hello world!'
         }
       }, {useMasterKey: true}))
+      .then(() => delayPromise(500)) // put a delay as we keep writing
       .then(() => {
         request.get({
           url: 'http://localhost:8378/1/classes/_PushStatus',