Refactors configuration management (#4271)

* Adds flow types / Configuration interfaces

* Lets call it options

* Use a single interface to generate the configurations

* Translates options to definitions only if comments are set

* improves logic

* Moves objects around

* Fixes issue affecting logging of circular objects

* fixes undefined env

* Moves all defaults to defaults

* Adds back CLI defaults

* Restored defaults in commander.js

* Merge provided defaults and platform defaults

* Addresses visual nits

* Improves Config.js code

* Adds ability to pass the default value in trailing comments

* Load platform defaults from the definitions file

* proper default values on various options

* Adds ParseServer.start and server.start(options) as quick startup methods

* Moves creating liveQueryServer http into ParseServer.js

* removes dead code

* Adds tests to guarantee we can start a LQ Server from main module

* Fixes incorrect code regading liveQuery init port

* Start a http server for LQ if port is specified

* ensure we dont fail if config.port is not set

* Specify port

* ignore other path skipped in tests

* Adds test for custom middleware setting

* Refactors new Config into Config.get

- Hides AppCache from ParseServer.js, use Config.put which validates

* Extracts controller creation into Controllers/index.js

- This makes the ParseServer init way simpler

* Move serverURL inference into ParseServer

* review nits

src/Controllers/LiveQueryController.js

@@ -1,10 +1,10 @@
 import { ParseCloudCodePublisher } from '../LiveQuery/ParseCloudCodePublisher';
-
+import { LiveQueryOptions } from '../Options';
 export class LiveQueryController {
   classNames: any;
   liveQueryPublisher: any;
 
-  constructor(config: any) {
+  constructor(config: ?LiveQueryOptions) {
     // If config is empty, we just assume no classs needs to be registered as LiveQuery
     if (!config || !config.classNames) {
       this.classNames = new Set();