make: add Ubuntu Zesty docker targets (.deb and ppa) Zesty Zapus was released on 2017-04-13 and will be supported until 2018-01.

docker: install less as a build-time dependency in deb-based distros It's needed since 387a76cac28e, otherwise dpkg-checkbuilddeps errors out.

py3: add utility to forward __str__() to __bytes__() It calls unifromlocal() instead of sysstr() because __bytes__() may contain locale-dependent values such as paths.

share: use dict literal instead of dict(key=value) check-code.py has the rule, but it isn't smart enough to catch this.