Do not scan whole file tree when making MANIFEST

Just use backports.unittest_mock so that tox can be invoked naturally (without having to specify an env).

improve certificate handling in SUSE Linux

Adding setuptools.command.py36compat module with functionality copied from distutils.command.sdist in 6d5603e41569

fix for extra names containing '-'

Follow PEP8 for keyword arguments syntax in setup

 Upgrade pyparsing to version 2.1.10

Find nested packages with excluded parent

`find_packages(exclude=['pkg'])` should still find and include the
`pkg.subpkg` package.

Fixes #808