Added specific path option to the 404 page

/projects/* and /grants/* are given different results containing a unique copy (editable in /admin/config/dosomething/dosomething_notfound) accompanied by campaign recommendations.

Fixes #3317

Let's make each of these copy variables required.  https://api.drupal.org/api/drupal/developer!topics!forms_api_reference.html/7#textfield