[ticket/12989] Remove unused "created_by.jpg"

This image is not used anywhere in prosilver.

PHPBB3-12989
Merge pull request #2893 from bantu/ticket/12989

[ticket/12989] Remove unused "created_by.jpg"

* bantu/ticket/12989:
  [ticket/12989] Remove unused "created_by.jpg"
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12989] Remove unused "created_by.jpg"