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/helper.js

@@ -24,7 +24,6 @@ if (global._babelPolyfill) {
 }
 
 var cache = require('../src/cache').default;
-var express = require('express');
 var ParseServer = require('../src/index').ParseServer;
 var path = require('path');
 var TestUtils = require('../src/TestUtils');
@@ -116,8 +115,6 @@ if (process.env.PARSE_SERVER_TEST_CACHE === 'redis') {
 const openConnections = {};
 
 // Set up a default API server for testing with default configuration.
-var app;
-var api;
 var server;
 
 // Allows testing specific configurations of Parse Server
@@ -131,17 +128,18 @@ const reconfigureServer = changedConfiguration => {
     }
     try {
       const newConfiguration = Object.assign({}, defaultConfiguration, changedConfiguration, {
-        __indexBuildCompletionCallbackForTests: indexBuildPromise => indexBuildPromise.then(resolve, reject)
+        __indexBuildCompletionCallbackForTests: indexBuildPromise => indexBuildPromise.then(resolve, reject),
+        mountPath: '/1',
+        port,
       });
       cache.clear();
-      app = express();
-      api = new ParseServer(newConfiguration);
-      api.use(require('./testing-routes').router);
-      app.use('/1', api);
-      app.use('/1', () => {
+      const parseServer = ParseServer.start(newConfiguration);
+      parseServer.app.use(require('./testing-routes').router);
+      parseServer.expressApp.use('/1', (err) => {
+        console.error(err);
         fail('should not call next');
       });
-      server = app.listen(port);
+      server = parseServer.server;
       server.on('connection', connection => {
         const key = `${connection.remoteAddress}:${connection.remotePort}`;
         openConnections[key] = connection;