[BUGFIX] Use namespaced class name for AJAX widget response

[BUGFIX] Use namespaced class name for AJAX widget response

Resolves: #67344
Releases: master
Change-Id: Ic78fce21dd8ff25caf8f6b9ede728bcaae124992
Reviewed-on: http://review.typo3.org/40065
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Frederic Gaus <frederic.gaus@flagbit.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>