Open and Iterative Policy Development

After healthy discussion with the community here on Project Open Data and through events like the Open License Data Jam, the White House is proposing edits to M-13-13 Open Data Policy to help clarify the intention of the Open License section and address concerns raised about the lack of reference to public domain. 

This is the first pull request proposing changes to the policy document itself, and before merging we want to feedback on the language to ensure it sufficiently addresses the concerns mentioned. Let us know if there are ways we could further improve this language!

Thanks again to everyone who has participated in these open license discussions to date--it genuinely has helped us improve the quality of our guidance, and we appreciate your time and thoughtfulness.