change crate.io references to pypi.python.org

Remove crate.io references on package.html and change to pypi.python.org.

crate.io domain was sold to bigdata company

http://www.reddit.com/r/Python/comments/1wcp93/what_happened_to_crateio/

crateio/crate.io#18

I think at the moment there is no substitute for crate.io.
Merge pull request #273 from luzfcb/patch-1

change crate.io references to pypi.python.org
Update CONTRIBUTORS.txt
Add @luzfcb to contributors
Merge pull request #6 from opencomparison/develop

latest from upstream