call password set for change password

Fixes #6514: advanced application SignupForm::signup() should not return User model if saving failed

Fixes #6404: advanced application template `Alert` widget was generating duplicate IDs in case of multiple flashes

Fixes #5088: new password reset token is now generated only if previous one was already used or expired

- Moved everything test-related into `tests` directory. Codeception tests are in `codeception`.
- Removed database module since we're using fixtures and migrations.
- Moved console entry points and bootstrap into `tests/codeception/bin`.
- Adjusted travis build scripts.
- Adjusted documentation to be consistent and reflect changes made.

`yii\web\Request::cookieValidationKey` is now automatically generated by the installation script for the basic and advanced application templates

- Removed hacks since these are no longer required: https://github.com/Codeception/Codeception/commit/71db233985531f298264dc4ca0160d2aa1c83b7f
- Removed unused helper classes
- Added 2.0 style "actor" to config

Thanks to @Ragazzo and @DavertMik for helping with it.

Fixes #4071: `mail` component renamed to `mailer`, `yii\log\EmailTarget::$mail` renamed to `yii\log\EmailTarget::$mailer`

Fixes #3979: Alert widget in advanced app is now able to display multiple flash messages of the same type

Fixes #3358: Removed automatic CSRF meta tag generation by `View`. Added `Html::csrfMetaTags()` and its call to main layout files

```
vendor/bin/indent --spaces -r framework/
vendor/bin/indent --tabs -r . --pattern=*.json
vendor/bin/indent --spaces -r . --pattern=*.md
vendor/bin/indent --spaces -r . --pattern=yii.*.js
vendor/bin/indent --spaces -r . --pattern=*.css
```

Fixes #3179: removed duplicate validation rules from User model in advanced app, removed User::create()