Upgrade pyparsing to version 2.1.8

Fix comparison with None.

Fix spacing after comment hash.

Add missing whitespace around operators.

Remove whitespace around parameter = sign.

Bundle the license

Update tox.ini envlist to match supported Pythons

Pythons 3.1, 3.2 are no longer supported, but Python 3.5, Pypy, and
Pypy3 are.

bump certifi to 2016.8.8

Add LICENSE file for expectant auditors

The classifier in setup.py should be enough for most auditors, but some
have automated tooling that checks for LICENSE files and reads those.
This helps all auditors (downstream redistributors and users) who can
not just rely on the classifier.

Related to #612

revert `library_dir_option` patch.

Revert patch on `distutils._msvccompiler.MSVCCompiler.library_dir_option`

See comments on #694.

quote library_dir_option after calling unpatched version

avoids double-quotes if the calling function does the quoting correctly.

Bump `certifi` to version `2016.8.2`