[SECURITY] Fix GeneralUtility::sanitizeLocalUrl to detect foreign schemes

This patch adds a check to be able to recognize arbitrary schemes which
have to be skipped. Furthermore a missing sanitation is added to
TYPO3\CMS\Backend\Controller\ContentElement\ElementInformationController

Resolves: #68825
Releases: master, 6.2
Security-Commit: de692804837ad0ddfdff194571dc8c786c717576
Security-Bulletin: TYPO3-CORE-SA-2015-009
Change-Id: Iddd54d241776a47f634c9ac2540e6a2e31801da7
Reviewed-on: http://review.typo3.org/43122


Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>