Fix print statements in demo_print_region.py for Python 3
Declare that pyregion supports Python 3 in setup.py
Update pyfits to astropy.io.fits in test scripts
Add entries to .gitignore
Change to public submodule URL in .gitmodules

This is needed to make pyregion testing on travis-ci.
See travis-ci documentation here:
http://about.travis-ci.org/docs/user/build-configuration/#Use-Public-URLs-For-Submodules
Add .travis.yml for testing on travis-ci.org
fix undefined _open_builtin error
Merge branch 'python3' of https://github.com/cdeil/pyregion
Merge remote-tracking branch 'cdeil/travis-ci'