tools/histogram_dump: improve io-latency and -size statistics

tools/histogram_dump: improve io-latency and -size statistics

The script is part of the ceph distribution but not
part of the official tooling. Nevertheless it was useful to understand
the usage scenarios of my osds.

- add colors to the output to ease interpretation
- add possibility to specify one ore more sockets
- aggregate statistics over multiple sockets
- prevent stacktrace if tool is interrupted by SIGINT
- add possibility to specify the number of data collection
  seconds between loops
- raise loop_seconds default

Signed-off-by: Marc Schoechlin <ms-github@256bit.org>