Benchmarks need to be updated

[bmoscon]

A skeleton of benchmarks exists in the top level directory, benchmarks. There are some very basic examples and a readme (https://github.com/manahl/arctic/blob/master/benchmarks.md), but these should be expanded upon to include all the storage engines and some more involved use cases and examples (i.e. chunkstore with numerics only, vs chunkstore with strings, version store with pickled objects, etc).

[dimosped]

@bmoscon this is a potential duplicate with #545
Do you mind if I merge the two?

I also plan to push a new branch which has lots of work on benchmarks (both as a framewework for ARctic and Arrow serializatoin vs Arctic).

[bmoscon]

yes thats fine, I was just adding this in the hopes someone would take it up :)