[GNC] move files into sub folder

[Karen Remick]

When I installed GnuCash I told it to put files in the folder for my 
business. I made the incorrect assumption that they'd be put into a 
file. Instead they are mixed in with the other files for my business. 
I'd like to put all the GnuCash files in one folder (let's call it 
GnuCashFiles) and have the program add any new files to that folder. How 
do I tell the program where the files are? I haven't seen the name of 
the file they are currently in, so I don't know what to edit.