Bring back tests for `options` argument of res.fetch*() methods

See:
https://github.com/Sannis/node-mysql-libmysqlclient/commit/43ca4e6499808eb0e9be0b8cf95932e93bb62b82
https://github.com/Sannis/node-mysql-libmysqlclient/commit/7b7b84414073c49af5ceeea5cc1efa8a93474b86

Also drop boolean variant of `options`.

Refs #95.
