Add du to CLI

[Kimahriman]

-du [-s] [-h] [-v] [-x] <path> ... :
  Show the amount of space, in bytes, used by the files that match the specified
  file pattern. The following flags are optional:
                                                                                 
  -s  Rather than showing the size of each individual file that matches the      
      pattern, shows the total (summary) size.                                   
  -h  Formats the sizes of files in a human-readable fashion rather than a number
      of bytes.                                                                  
  -v  option displays a header line.                                             
  -x  Excludes snapshots from being counted.                                     
  
  Note that, even without the -s option, this only shows size summaries one level
  deep into a directory.
  
  The output is in the form 
        size    disk space consumed     name(full path)