docs: Comment out html_static_path setting.

There are no static elements, so this just silences a warning.
Use print function instead of statement.
Correct docstring example of domain_of_validity.
Use print() for all docstring examples.
Add version classifiers for PyPI.

I only added the versions I tested.
Enable testing on Travis.
Update version number in docs.
Trim as_proj4 result.
Merge pull request #2 from QuLogic/py3k

Python 3 and Travis support
Merge pull request #1 from QuLogic/doc-tweaks

Documentation tweaks