not-found clients are revoked

[halaei]

The current code does not work if someone deletes the record from DB. It is a security risk I guess.

[taylorotwell]

This is very hard to read with the negative boolean checks.

[taylorotwell]

I still have no idea what this is doing. Needs to be re-written.

[halaei]

This also works, but is slightly less efficient:

    public function revoked($id)
    {
        return ! $this->findActive($id);
    }

Will it be fine?