Fixed a few issues in the disk_access code. See comments

1. Now the utility downloads any kind of file (not just text file) from the disk image.
2. The files are copied in the export directory in the same directory hierarchy as seen in the image. (It originally dumped all files in the output directory)
Issues: 
1. The warning statement about addRow is still showing up, but doesn't affect the functionality
2. When downloading more than 4 files at time, the following error message shows up :+1: 
"IOError: [Errno 4] Interrupted system call"
Alternative is to copy 3-4 files at a time till the problem is fixed.