[ticket/12611] Remove phpBB Group copyright notice from .gifs

PHPBB3-12611
Merge pull request #2511 from Marshalrusty/ticket/12611

[ticket/12611] Remove phpBB Group copyright notice from .gifs

* Marshalrusty/ticket/12611:
  [ticket/12611] Remove phpBB Group copyright notice from .gifs
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12611] Remove phpBB Group copyright notice from .gifs