[TASK] Raise version to 2.0.0-dev

Change-Id: Ie08099047925879c620c91c7e6091806849bacbf
Reviewed-on: http://review.typo3.org/33231
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>