Some more changes related to MR 1783. Adding a histogram option for the summary jobs action.

[root@uio-atlas-ce1 control]# arcctl datastaging summary jobs --showhist -h
usage: arcctl datastaging summary jobs [-h] [-d DAYS] [-hr HOURS] [-m MINUTES] [-s SECONDS] [-sh]

optional arguments:
  -h, --help            show this help message and exit
  -d DAYS, --days DAYS  Timewindow in days.
  -hr HOURS, --hours HOURS
                        Timewindow in hours.
  -m MINUTES, --minutes MINUTES
                        Timewindow in minutes.
  -s SECONDS, --seconds SECONDS
                        Timewindow in seconds.
  -sh, --showhist       Print out ASCII histograms of the datastaging summary. Requires numpy.