pep8 style for sys_stat

White space changes only, but makes some tools behave better, and have
less squiggly lines.  2 spaces evil! 4 spaces good! free thought evil!
sys_stat: use argparse instead of manual arg parsing.

This of course is a breaking change for python < 2.7,
they need to "pip install argparse" which adds argparse support all the
way back to python 2.2

One minor difference vs original is that original filename is kept as
column heading.  Originally the argument was -F filename:tag which is
marginally useful for dealing with filenames with spaces in them, but
just confusing and overcomplicated for mortals IMO.
Better support operating in a virtual environment.

Follow "normal" python shebang practice.