Fixed long description content type

Fixed long description content type

Fixed image URL in README.md

PyPi.org cannot handle relative image URLs like GitHub can, so made the image URL ablsolute.

Added a demo module

Added a demo module, updated README, and bumped version.

First official release

This is the first feature complete release.

Fixed illegal classifier in setup.py for pypi.org's happiness

Fixed illegal classifier in setup.py for pypi.org's happiness