[TASK] Raise version to 2.2.1-dev

Change-Id: I3496dc4c03a31ba535bbf012587d2c221c8e4948
Reviewed-on: http://review.typo3.org/35343
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>