[BUGFIX] Remove duplicate domain from FE copyright comment

Since typo3.com was replaced by typo3.org, current frontend copyright
comment shows duplicate domain in copyright:
TYPO3 is copyright 1998-2012 of Kasper Skaarhoj. Extensions are
copyright of their respective owners. Information and contribution
at http://typo3.org/ and http://typo3.org/

Change-Id: Id0647274974032f20a1b5a050e439ed43213bcdb
Fixes: #36164
Releases: 4.5, 4.6, 4.7, 6.0
Reviewed-on: http://review.typo3.org/10818
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn