Fix soft-delete does not sync original.

[Jafa80]

Currently when we are soft-deleting model original is not synced. This causes an issue when model is deleted and restored without getting fresh data from database it actually stays deleted.

Here is an example of this happening in artisan:

>>> $model = App\Models\MyModel::find("HAKXFY")
=> App\Models\MyModel {#684
     id: "HAKXFY",
     created_at: "2018-05-31 15:56:13",
     updated_at: "2018-05-31 15:56:13",
     deleted_at: null,
   }
>>> $model->delete()
=> true
>>> App\Models\MyModel::find("HAKXFY")
=> null
//model is still dirty
>>> $model->getDirty();
=> [
     "updated_at" => "2018-05-31 15:58:12",
     "deleted_at" => "2018-05-31 15:58:12",
   ]
>>> $model->restore();
=> true
//Model is clean now
>>> $model->getDirty();
=> []
//While model instance thinks he's restored
>>> $model
=> App\Models\MyModel {#684
     id: "HAKXFY",
     created_at: "2018-05-31 15:56:13",
     updated_at: "2018-05-31 15:58:12",
     deleted_at: null,
   }
// Actual results from DB are different
>>> App\Models\MyModel::find("HAKXFY")
=> null
>>> App\Models\MyModel::withTrashed()->find("HAKXFY")
=> App\Models\MyModel {#689
     id: "HAKXFY",
     created_at: "2018-05-31 15:56:13",
     updated_at: "2018-05-31 15:58:12",
     deleted_at: "2018-05-31 15:58:12",
   }

[taylorotwell]

I am closing this pull request because it lacks sufficient explanation, tests, or both. It is difficult for us to merge pull requests without these things because the change may introduce breaking changes to the framework.

Feel free to re-submit your change with a thorough explanation of the feature and tests - integration tests are preferred over unit tests. Please include it's benefit to end users; the reasons it does not break any existing features; how it makes building web applications easier, etc.

Thanks!