* master: (30 commits)
  Added SerialColumn to crud generated code.
  Added ActionColumn. crud generator WIP.
  Fixes #823: consistent interface naming
  Advanced application template: Delete flash message after it was displayed
  Fixes #901: Added $delete parameter to Session::getFlash().
  Polished up the basic discussion of template alternatives
  Advanced application template: removed unused scenario from User model
  porting the fix from https://github.com/yiisoft/yii/pull/2894
  Edited introduction
  Fixes #898: supported different signature of MemCache::addServer().
  Fixes #897.
  Use str_replace() rather than implode-explode
  Fix parenthesis typo in CRUD index template
  Doing more editing...
  test break fix.
  Support ajax redirection.
  Enable CSRF validation by default.
  Supports more elements to use data-confirm and data-method attributes.
  refactored Request::validateCsrfToken().
  Fixed CSRF validation bug.
  ...