Feature/write through cache perf

-> Adds in a caliper project, and a benchmark

-> Add in a HHFiltered store, we use a local mutable CMS sketch to keep track of heavy hitters, only storing those in the cache. Yields drop in read I/O by 30%
Was wondering if this can be made a `ConcurrentHashMap`. But looks like it can't because an update here optionally performs pruning which needs a global view of the hash map?