Enable SSUBSCRIBE benchmark mode

[filipecosta90]

Fixes #8

• It uses go-redis instead of radix given go-redis is now under redis org.
• It uses changes proposed to go-redis in Avoid CLIENT SETNAME command when using HELLO redis/go-redis#2570 to be able to specify the protocol of the benchmark.
• It introduces the mode option to use either subscribe or ssubscribe command.