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/ValidationAndPasswordsReset.spec.js

@@ -18,7 +18,7 @@ describe("Custom Pages, Email Verification, Password Reset", () => {
       publicServerURL: "https://my.public.server.com/1"
     })
       .then(() => {
-        var config = new Config("test");
+        var config = Config.get("test");
         expect(config.invalidLinkURL).toEqual("myInvalidLink");
         expect(config.verifyEmailSuccessURL).toEqual("myVerifyEmailSuccess");
         expect(config.choosePasswordURL).toEqual("myChoosePassword");
@@ -849,7 +849,7 @@ describe("Custom Pages, Email Verification, Password Reset", () => {
             expect(response.body).toEqual('Found. Redirecting to http://localhost:8378/1/apps/password_reset_success.html?username=zxcv');
 
             Parse.User.logIn("zxcv", "hello").then(function(){
-              const config = new Config('test');
+              const config = Config.get('test');
               config.database.adapter.find('_User', { fields: {} }, { 'username': 'zxcv' }, { limit: 1 })
                 .then(results => {
                 // _perishable_token should be unset after reset password