Fix typing module issues

The typing module is not yet stable (it was included provisionally) and typing_inspect does not work for certain versions that are still used by some Linux distributions (i.e. Ubuntu Xenial uses 3.5.2 instead of 3.5.3, where typing_inspect works differently). We need to take those somewhat into account.

Setup.py fix

In setup.py, the requires argument was replaced with install_requires because dependencies weren't automatically installed.

Partial PEP-484 support

The typing.Union, typing.Optional and typing.Callable annotations were implemented to replace the tuple notation and the use of the callable method as annotations. Those are deprecated and will be removed from a future release.

Version support changes

Dropping unsupported Python versions 3.2 and 3.3 and introduce support for version 3.6.

Import fix

See issue #13

Pytest support

• @nicoddemus added support for py.test.
• Minor cleanups in the testing infrastructure (removed Makefile, rely solely on tox, etc.)
• Long description was fixed in setup.py

Initial release

Initial release in which we moved the codebase from the internal repository over to github.