[FEATURE] Enhance ajax api to select by integer parent id

Change-Id: Ic8aaa0728a43936cd4c6e1ed590e01ca8f0fbf5b
Reviewed-on: http://review.typo3.org/32893
Reviewed-by: Sebastian Fischer <typo3@evoweb.de>
Tested-by: Sebastian Fischer <typo3@evoweb.de>