RPOPLPUSH, Set, and Sorted Set Operation Support

I've added support for RPOPLPUSH, SDIFF, SDIFFSTORE, SINTER, SINTERSTORE, SMOVE, SUNION, SUNIONSTORE, ZINTERSTORE, and ZUNIONSTORE.  I added calls similar to what were in redis-check.sh, and they all seem to be working properly.

Let me know if this looks ok(we're also planning to use these operations in our code).  I'm happy to make any changes necessary to get this merged.

Best Regards,

Dan