Update all .py source files by
$ pyupgrade --py3-only $(git ls-files | grep ".py$")
to modernize the code according to Python 3 syntaxes.
pep8 errors are fixed by
$ autopep8 --select=E127,E128,E501 --max-line-length 79 -r \
--in-place heatclient
and a few manual adjustments.
Also replace a few remaining usage of %s by format or join.
Change-Id: I054046b414f809ff2e390713dd605f3732064148
d5756db596