[5.3] Implement oracle user provider.

[yajra]

When using oracle, we may encounter a problem on authentication because oracle queries are case sensitive by default.

By using this oracle user provider, we will now be able to avoid user issues when logging in and doing a forgot password failure because of case sensitive search.

To use, just update auth.php config and set the driver to oracle

'providers' => [
    'users' => [
        'driver' => 'oracle',
        'model' => App\User::class,
    ],
]