Adding histogrms to storage_proxy
Adding histogrms to storage_proxy

The storage proxy needs to collect statistics about read, write and
range. For that the ihistogram object was added to its stats object.

Signed-off-by: Amnon Heiman <ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@cloudius-systems.com>

eklitzke/scylla,scylladb/scylla,respu/scylla,guiquanz/scylla,scylladb/scylla,wildinto/scylla,raphaelsc/scylla,asias/scylla,kangkot/scylla,rluta/scylla,gwicke/scylla,gwicke/scylla,asias/scylla,dwdm/scylla,kjniemi/scylla,rluta/scylla,avikivity/scylla,bowlofstew/scylla,scylladb/scylla,victorbriz/scylla,capturePointer/scylla,aruanruan/scylla,guiquanz/scylla,glommer/scylla,dwdm/scylla,respu/scylla,dwdm/scylla,acbellini/scylla,phonkee/scylla,tempbottle/scylla,rentongzhang/scylla,stamhe/scylla,tempbottle/scylla,shaunstanislaus/scylla,linearregression/scylla,wildinto/scylla,wildinto/scylla,justintung/scylla,eklitzke/scylla,duarten/scylla,aruanruan/scylla,rentongzhang/scylla,linearregression/scylla,glommer/scylla,capturePointer/scylla,phonkee/scylla,phonkee/scylla,stamhe/scylla,respu/scylla,raphaelsc/scylla,kjniemi/scylla,shaunstanislaus/scylla,shaunstanislaus/scylla,duarten/scylla,avikivity/scylla,eklitzke/scylla,avikivity/scylla,asias/scylla,raphaelsc/scylla,bowlofstew/scylla,senseb/scylla,senseb/scylla,gwicke/scylla,capturePointer/scylla,kjniemi/scylla,rentongzhang/scylla,stamhe/scylla,linearregression/scylla,victorbriz/scylla,acbellini/scylla,bowlofstew/scylla,senseb/scylla,victorbriz/scylla,kangkot/scylla,kangkot/scylla,justintung/scylla,aruanruan/scylla,scylladb/scylla,acbellini/scylla,guiquanz/scylla,duarten/scylla,justintung/scylla,rluta/scylla,tempbottle/scylla,glommer/scylla