Added the MOVE command to finagle-redis.

Finagle-redis does not implement all valid redis commands. Before embarking to flesh out
remaining commands, I want to verify that any commands added are done in the correct
testing and stylistic manner.

The MOVE command has been added as a Key command

Tested with Scala 2.9.2, 2.10.3, 2.11.0
Tested with Redis 2.8