2 new functions: undelete and set_restriction

```undelete```: pretty self-explanatory, works only when soft deleting is enabled
```set_restriction```: **use-case:** controller’s constructor loads a model, adds a restriction (eg. “user_id = 123”), subsequent calls to the model add the restriction to all the queries. Think of it as an easy built-in security which removes the need to add the same where clause again and again on all methods.