You could use either of the following solutions:
Change your class declaration to:
class User extends \Eloquent implements \UserInterface, \RemindableInterface
Or, simply remove the line:
namespace MyApp\Models;
I would recommend taking the second solution (removing the namespace) for now, until you are comfortable with namespaces in PHP.
Additionally, you should be using RevisionableTrait, not Revisionable, e.g.,
<?php
use Illuminate\Auth\UserInterface;
use Illuminate\Auth\Reminders\RemindableInterface;
class User extends Eloquent implements UserInterface, RemindableInterface {
use Venturecraft\Revisionable\RevisionableTrait;