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/ParseGlobalConfig.spec.js

@@ -5,7 +5,7 @@ const Config = require('../src/Config');
 
 describe('a GlobalConfig', () => {
   beforeEach(done => {
-    const config = new Config('test');
+    const config = Config.get('test');
     const query = on_db('mongo', () => {
       // Legacy is with an int...
       return { objectId: 1 };
@@ -147,7 +147,7 @@ describe('a GlobalConfig', () => {
   });
 
   it('failed getting config when it is missing', (done) => {
-    const config = new Config('test');
+    const config = Config.get('test');
     config.database.adapter.deleteObjectsByQuery(
       '_GlobalConfig',
       { fields: { params: { __type: 'String' } } },