- 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.

```
interface IdentityInterface
{
    /**
     * Finds an identity by the given ID.
     * @param string|integer $id the ID to be looked for
     * @return IdentityInterface the identity object that matches the given ID.
     * Null should be returned if such an identity cannot be found
     * or the identity is not in an active state (disabled, deleted, etc.)
     */
    public static function findIdentity($id);
```

Fixes #4147

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

fixed application config for unit test

This reverts commit 2bb6f135.