* 'master' of github.com:yiisoft/yii2:
  Removed unused namespace.
  Put back Yii::getObjectVars() and fixed infinite loop in Object::toArray().
  Recursively return previous exceptions in toArray().
  Added previous exception in toArray().
  Removed headers in ErrorHandler.

fix MigrateController

Added support for different response formats.
Support for error response in different formats.

load ErrorException manually because autoloading them will not work
when error occurs while autoloading a class

Call static::mkdir(...)

Compose Message Command