More fixes to symposion.sponsorship.tests.
More fixes to symposion.sponsorship.tests.

  - Fix tests that use staff_member_required decorator to redirect to
    admin login page.
  - Don't claim that `sponsor_zip_logo_files` method only downloads
    print and web logos when the automated tests don't validate this and
    there is no actual code in the method that does this.
  - Fix broken folder names for print and web logos (go figure).
  - Fix benefit validation tests to reflect that the database doesn't
    really validate text benefits don't have files or logo benefits
    don't have text (Note that this makes all benefit validation tests
    return True).

pydata/conf_site,pydata/conf_site,pydata/conf_site