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

spec/InstallationsRouter.spec.js

@@ -5,7 +5,7 @@ var InstallationsRouter = require('../src/Routers/InstallationsRouter').Installa
 
 describe('InstallationsRouter', () => {
   it('uses find condition from request.body', (done) => {
-    var config = new Config('test');
+    var config = Config.get('test');
     var androidDeviceRequest = {
       'installationId': '12345678-abcd-abcd-abcd-123456789abc',
       'deviceType': 'android'
@@ -43,7 +43,7 @@ describe('InstallationsRouter', () => {
   });
 
   it('uses find condition from request.query', (done) => {
-    var config = new Config('test');
+    var config = Config.get('test');
     var androidDeviceRequest = {
       'installationId': '12345678-abcd-abcd-abcd-123456789abc',
       'deviceType': 'android'
@@ -81,7 +81,7 @@ describe('InstallationsRouter', () => {
   });
 
   it('query installations with limit = 0', (done) => {
-    var config = new Config('test');
+    var config = Config.get('test');
     var androidDeviceRequest = {
       'installationId': '12345678-abcd-abcd-abcd-123456789abc',
       'deviceType': 'android'
@@ -100,7 +100,7 @@ describe('InstallationsRouter', () => {
       info: {}
     };
 
-    new Config('test');
+    Config.get('test');
     var router = new InstallationsRouter();
     rest.create(config, auth.nobody(config), '_Installation', androidDeviceRequest)
       .then(() => {
@@ -118,7 +118,7 @@ describe('InstallationsRouter', () => {
   });
 
   it('query installations with count = 1', done => {
-    var config = new Config('test');
+    var config = Config.get('test');
     var androidDeviceRequest = {
       'installationId': '12345678-abcd-abcd-abcd-123456789abc',
       'deviceType': 'android'
@@ -154,7 +154,7 @@ describe('InstallationsRouter', () => {
   });
 
   it('query installations with limit = 0 and count = 1', (done) => {
-    var config = new Config('test');
+    var config = Config.get('test');
     var androidDeviceRequest = {
       'installationId': '12345678-abcd-abcd-abcd-123456789abc',
       'deviceType': 'android'