Packaging

[GhostofGoes]

Converted to a Python package using setuptools.

Packaging changes

• Converted to a Python package. python -m killer will call __main__.py, which calls main() in killer.py.
• Added a setup.py to create a package
• Added requirements.txt with required dependencies for Windows
• Added dev-requirements.txt with necessary packages for creating and uploading a package to PyPI, plus some other useful things

Other changes

• Fixed a bug with network interfaces on Windows
• Added finer grained detection of the platform using module-global variables (WINDOWS, POSIX, etc.)
• Add .gitignore for Git

To install for development: python setup.py install or pip install -e . To cut a release: python setup.py release (this is configured in setup.cfg)