Adding "precise" flag for naturaltime/delta which outputs tenths of integers

[leopd]

I often find it confusing and unhelpful for humanize to represent everything between 1.000 and 1.999 as 1, as in:

>>> humanize.naturaltime(datetime.datetime.now() - datetime.timedelta(seconds=7000))
'an hour ago'

So I added a precise flag to naturaltime and naturaldate so they'll output tenths, as in:

>>> humanize.naturaltime(datetime.datetime.now() - datetime.timedelta(seconds=7000), precise=True)
'1.9 hours ago'

[hugovk]

🚀 Development has moved to https://github.com/python-humanize/humanize 🚀

Please open new PRs at https://github.com/python-humanize/humanize/pulls