The ExtJS4 skin has an superfluous CSS file
and the Ruby configuration file is wrong.

Fixes: #32932
Releases: 4.7
Change-Id: Id6662d6cece570bd2acea8875287db61f4ad858e
Reviewed-on: http://review.typo3.org/7651
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter