BUG: #2326 make save dialog name match node name

With this change, the file save name will be made to match the
name of the node.  This way when a user has specified a
meaningful name in the GUI it will be transferred to the
filename as well for consistency.

http://www.na-mic.org/Bug/view.php?id=2326#c8637

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22004 3bd1e089-480b-0410-8dfb-8563597acbee