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/ParseAPI.spec.js

@@ -23,7 +23,7 @@ describe_only_db('mongo')('miscellaneous', () => {
       obj.set('foo', 'bar');
       return obj.save();
     }).then(() => {
-      const config = new Config(appId);
+      const config = Config.get(appId);
       return config.database.adapter.find('TestObject', { fields: {} }, {}, {});
     }).then((results) => {
       expect(results.length).toEqual(1);
@@ -151,7 +151,7 @@ describe('miscellaneous', function() {
   });
 
   it('ensure that if people already have duplicate users, they can still sign up new users', done => {
-    const config = new Config('test');
+    const config = Config.get('test');
     // Remove existing data to clear out unique index
     TestUtils.destroyAllDataPermanently()
       .then(() => config.database.adapter.createClass('_User', userSchema))
@@ -183,7 +183,7 @@ describe('miscellaneous', function() {
   });
 
   it('ensure that if people already have duplicate emails, they can still sign up new users', done => {
-    const config = new Config('test');
+    const config = Config.get('test');
     // Remove existing data to clear out unique index
     TestUtils.destroyAllDataPermanently()
       .then(() => config.database.adapter.createClass('_User', userSchema))
@@ -211,7 +211,7 @@ describe('miscellaneous', function() {
   });
 
   it('ensure that if you try to sign up a user with a unique username and email, but duplicates in some other field that has a uniqueness constraint, you get a regular duplicate value error', done => {
-    const config = new Config('test');
+    const config = Config.get('test');
     config.database.adapter.addFieldIfNotExists('_User', 'randomField', { type: 'String' })
       .then(() => config.database.adapter.ensureUniqueness('_User', userSchema, ['randomField']))
       .then(() => {
@@ -1546,7 +1546,7 @@ describe_only_db('mongo')('legacy _acl', () => {
       },
       json: true
     }).then(() => {
-      const config = new Config('test');
+      const config = Config.get('test');
       const adapter = config.database.adapter;
       return adapter._adaptiveCollection("Report")
         .then(collection => collection.find({}))