This patch adds the implmentation for the read, write and range
estimated histogram and total latency.
After this patch the following url will be available:
/storage_proxy/metrics/read/estimated_histogram/
/storage_proxy/metrics/read
/storage_proxy/metrics/write/estimated_histogram/
/storage_proxy/metrics/write
/storage_proxy/metrics/range/estimated_histogram/
/storage_proxy/metrics/range
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
14482d4496