Bugfix/paranoid: paranoidClause problem without timestamps

If you set `timestamps` off, but keep `paranoid` on, `paranoid` will be useless, and it happens on some cases. Because of this problem, `paranoidClause` was failing on models that doesn't have `timestamps`, that will result `this._timestampAttributes` as an empty array and `this._timestampAttributes.deletedAt` will be undefined.

I got this error on Migrator `SequelizeMeta` model because my entire database is `paranoid` and `SequelizeMeta` doesn't use `timestamps`.

This PR is RTM (ready to merge).