Edited Issue: No Default Due Date Option [280]

Would it be possible to have the option for no Due Date? For many issues we don't know the Due Date when adding a new issue. Or the Due Date may be sometime way off in the future so riddling everything with a Due Date messes up views and filters.

So, we typically clear out the Due Date whenever adding a new issue. Since this is sometimes missed, it would be nice to have a default option of "No Due Date".