SI-7355 Handle spaces in paths in Windows batch files.

Changed "%1%" and %2% to "%~1" and %~2 to allow spaces
in paths by surrounding quotes according to advice at:

  http://stackoverflow.com/questions/473117/pass-path-with-spaces-as-parameter-to-bat-file
  http://ss64.com/nt/syntax-args.html
Merge pull request #2435 from retronym/ticket/7355

SI-7355 Handle spaces in paths in Windows batch files.