Add forward slash to each argument in argsToPath

- The argsToPath method now adds a trailing forward slash to each
  argument passed in. This may result in double forward slashes
  in path strings when the application is appified.

- Updated the file method to remove double forward slashes from
  the extension argument at runtime. The method will check to
  see if the extension is a URL and not replace the double
  forward slashes in the scheme portion of the URL (e.g. http://,
  file:///, etc.).