Preview thumbnails and details-view updated in the file listing


Files modified:


1) urls/file.py
   - Following urls added:-
     - 'getFileThumbnail' - for getting thumbnails
     - 'file_detail' - for getting file details-view
     
2) views/file.py
   - Following views added:-
     - 'getFileThumbnail' - for respective url specified above
     - 'file_detail' - for respective url specified above
     
3) templates/ndf/file.html
   - Urls modified that updates following:
     - Preview thumbnail works in the file listing
     - 'View details' in the file listing gives proper details-view