Added MainWindow and buttons off "Edit" to select all and deselect all files.
Added push/Buttons Close and Export. Added functionality to click on
text files and export them to specified directory.
If image type is not aff or e01, premis events are not generated as
we use image type sensitie commands like affinfo for premis xml generation.
Merge branch 'master' of https://github.com/sunithamisra/bitcurator
Now the utility downloads any type of file, and in the same directory
structure as what is found on the image.
Merge pull request #54 from sunithamisra/master

Fixed a few issues in the disk_access code. See comments