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/Uniqueness.spec.js

@@ -9,7 +9,7 @@ describe('Uniqueness', function() {
     obj.set('unique', 'value');
     obj.save().then(() => {
       expect(obj.id).not.toBeUndefined();
-      const config = new Config('test');
+      const config = Config.get('test');
       return config.database.adapter.ensureUniqueness('UniqueField', { fields: { unique: { __type: 'String' } } }, ['unique'])
     })
       .then(() => {
@@ -30,7 +30,7 @@ describe('Uniqueness', function() {
     obj.save({ string: 'who cares' })
       .then(() => obj.save({ ptr: obj }))
       .then(() => {
-        const config = new Config('test');
+        const config = Config.get('test');
         return config.database.adapter.ensureUniqueness('UniquePointer', { fields: {
           string: { __type: 'String' },
           ptr: { __type: 'Pointer', targetClass: 'UniquePointer' }
@@ -58,7 +58,7 @@ describe('Uniqueness', function() {
     o2.set('key', 'val');
     Parse.Object.saveAll([o1, o2])
       .then(() => {
-        const config = new Config('test');
+        const config = Config.get('test');
         return config.database.adapter.ensureUniqueness('UniqueFail', { fields: { key: { __type: 'String' } } }, ['key']);
       })
       .catch(error => {
@@ -68,7 +68,7 @@ describe('Uniqueness', function() {
   });
 
   it_exclude_dbs(['postgres'])('can do compound uniqueness', done => {
-    const config = new Config('test');
+    const config = Config.get('test');
     config.database.adapter.ensureUniqueness('CompoundUnique', { fields: { k1: { __type: 'String' }, k2: { __type: 'String' } } }, ['k1', 'k2'])
       .then(() => {
         const o1 = new Parse.Object('CompoundUnique');