[RELEASE] Release of TYPO3 6.1.2

Change-Id: I488700726d337e3e19e979a52a86ac9c1ab8084a
Reviewed-on: https://review.typo3.org/22517
Reviewed-by: TYPO3 Release Team
Tested-by: TYPO3 Release Team
[TASK] Set TYPO3 version to 6.1.3-dev

Change-Id: I59ed376c317bbda9a43b7a377587dcce3907c714
Reviewed-on: https://review.typo3.org/22518
Reviewed-by: TYPO3 Release Team
Tested-by: TYPO3 Release Team