BUG: Ensure module widget listen to mrmlSceneChanged signal

This is a follow-up on commit r21613 where the connections haven't been
updated as expected.

Fixes #2247

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21615 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Remove redundant connections from qSlicerWelcomeModuleWidget

Fix warning:

Object::connect: No such slot qSlicerWelcomeModuleWidget::loadData() in /home/jchris/Projects/Slicer-AHM-Superbuild-Debug/Slicer-build/Modules/Loadable/SlicerWelcome/ui_qSlicerWelcomeModuleWidget.h:293
Object::connect: (sender name: 'LoadNonDicomDataButton')
Object::connect: (receiver name: 'qSlicerWelcomeModuleWidget')


See #2247

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21616 3bd1e089-480b-0410-8dfb-8563597acbee