Add model factory type provider

[JanisVepris]

Provides some type for most common factory() usage.

In all following cases IDE resolves $user as the User model.

$user = factory(User::class)->create();

$user = factory(User::class)->make();

$user = factory(User::class)->state('some-state')->create();

$user = factory(User::class)->state('deleted')->states(['deteled', 'signedUp'])->make();

$userFactory = factory(User::class);
$user = $userFactory->state('deleted')->create();

$type = User::class;
$user = factory($type)->create();

$type = User::class;
$userFactory = factory($type);
$user = $userFactory->create();

$user = factory('App\Model\User')->create();

In this case it resolves $users as Illuminate\Database\Eloquent\Collection

$users = factory(User::class, 3)->create();