Fixed Python 3 compatibility
Added Python version classifiers to indicate min/max Python versions
Added tox configuration to easily test cross-version Python compatibility
Moved pytest configuration to setup.cfg and added wheel configuration
Made the codebase PEP 8 compliant (save for the line length limitation)
Merge pull request #1 from agronholm/master

Fixed Python 3 compatiblity and cleaned up code for PEP 8 compliancy