Add more caches to benchamark

[janisz]

We should add following caches to our benchmark set

• https://github.com/dgraph-io/ristretto
• https://github.com/VictoriaMetrics/fastcache
• https://github.com/goburrow/cache

[cristaloleg]

Related to allegro/bigcache#162
It's fine to make such benchmarks, but eventually all of them will be in another repo.

[janisz]

Hmm, maybe we should move bigcache to its own org and keep all related repositories under the same org?

[siennathesane]

I think this would be a good idea.