Merge branch 'fio-histo-log-pctiles' of https://github.com/parallel-fs-utils/fio

* 'fio-histo-log-pctiles' of https://github.com/parallel-fs-utils/fio:
  design document for tools/hist/fio-histo-log-pctiles.py
  switch to argparse module for CLI parsing
  use interpolation for more accurate percentile calculation
  get latency percentiles over time from fio histo logs