[RELEASE] Release of TYPO3 6.0.6

Change-Id: I7898f71d81b807a859cd9d8760e4bc9b133a567f
Reviewed-on: https://review.typo3.org/21030
Reviewed-by: TYPO3 Release Team
Tested-by: TYPO3 Release Team
[TASK] Set TYPO3 version to 6.0.7-dev

Change-Id: Ic3f4607c706bb9200e74e18907465a09ba899062
Reviewed-on: https://review.typo3.org/21031
Reviewed-by: TYPO3 Release Team
Tested-by: TYPO3 Release Team