This patch close the gap between the storage_proxy read, write and range
metrics and the API.
For each of the metrics there will be a histogram, estimated histogram
and total.
The patch contains the definitions for the following:
get_read_estimated_histogram
get_read_latency
get_write_estimated_histogram
get_write_latency
get_range_estimated_histogram
get_range_latency
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
need mrege storage_proxy