Fixes #4252, Fixes #3171 Fixed Codeception
Codeceoption adjustments

- 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.
`yii\web\Request::cookieValidationKey` is now automatically generated by the installation script for the basic and advanced application templates
Request::cookieValidationKey must be explicitly specified now.
Merge remote-tracking branch 'upstream/master'