[bug] Added two tests to show inconsistent order_by behavior

@josiahcarlson 

I ran into some really funky behavior when I was doing `query`es without `filter`s and with `order_by`.  At first I thought it wasn't working at all, but it's actually working for integer columns but not for string/text.

I investigated a little but I hit a wall at the `conn.pipeline()` object.  

`test_naked_order_by_num` passes, and `test_naked_order_by_string` fails.

https://travis-ci.org/pconerly/rom/builds/39043270

I'm not sure if this is a bug with rom or with redis?