pp: add --humanize | -H to

[yarikoptic]

ATM even with pretty-printing hard to get a good idea on how much memory was used and requires translation of time from seconds. With -H pp should not print json as is, but first humanize known records and otherwise floating point numbers for more humane consumption and only then print, e.g. instead of

 'execution_summary': {'average_pcpu': 978.0139225181615,
                       'average_pmem': 0.03751008878127522,
                       'average_rss': 451305015.7869248,
                       'average_vsz': 522215819.88054895,

have

 'execution_summary': {'average_pcpu': '978.01%',
                       'average_pmem': '0.03%',
                       'average_rss': '451.3 MB',
                       'average_vsz': '522.2 MB',