[BUGFIX] Additions to fileDenyPattern give security warning in BE

The check is wrong. Instead of checking if the entry is equal to default entry, it should check if any parts of the default value are removed.

As it's a security warning, this should be stated in the warning, so change the wording.

Change-Id: If20d362bef39a4d8533a54e8124b4913b9dcb55e
Resolves: #M17817
Reviewed-on: http://review.typo3.org/1031


Tested-by: Andreas Wolf <andreas.wolf@ikt-werk.de>
Reviewed-by: Steffen Ritter <info@rs-websystems.de>
Tested-by: Steffen Ritter <info@rs-websystems.de>
Reviewed-by: Andreas Wolf <andreas.wolf@ikt-werk.de>