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