Added advanced application configs schema to docs, fixed the fact that there's now common/config/main.php

Cleaner environments for yii2-advanced-app

fixes #2196

* 'master' of github.com:yiisoft/yii2:
  Added `yii\web\View::POS_LOAD`

realpath(false) = current working directory.
This can cause problems with getAlias() which returns false.

see yiisoft/yii#3113

fixes yiisoft/yii#2844

which resulted in endless loop

http://www.yiiframework.com/forum/index.php/topic/50982-cfilehelper-bug-security-flaw/

Added `yii\web\Request::get($name = null, $defaultValue = null)` and `yii\web\Request::post($name = null, $defaultValue = null)`

removed getPostParam() from Request, body is $_POST by default

CS fix.

* 'master' of github.com:yiisoft/yii2:
  added more tests.

fixes #2184

fix the _only_ option in calls to FileHelper::findFiles()