* Added 'return' to goHome() calls in actions
* Changed $_POST to Yii::$app->request->post()

fixes #2099

Modified application templates so when trying to log in when already logged in it just redirects to homepage instead of throwing exceptions

- Turned on CSRF validation by default.
- Added access control for login, signup and logout for frontend application.
- Added access control for login, logout and index for backend application.
- YII_ENV is now defined for all applications.
- No trace is writted to logs if debug is turned off.
- Added default error view for frontend and backend.
- In frontend application captcha will always ask for "testme" if YII_ENV is defined as "test".

- Unified way to use Alert
- Added link to restore password to login form
- Refactored restore password

This reverts commit 9d7597d6, reversing
changes made to 6b6390f7.