Sorting with multiple GETs fails to STORE

Hi,

I encountered an issue when trying to run a `SORT` that used multiple `GET` parameters and also `STORE`s the result. The problem was that if there were multiple `GET` parameters, the `Redis#sort` method was trying to process the reply from the Redis client as if it was an array. However, if this is combined with a `STORE` parameter, the reply will be an integer denoting how many items were stored in the given list.

This pull request fixes that, and I've included a test case for it.

Thanks!