Correction to solve subprocess issue on Windows.

Problem with 64-bit versions of Windows (in my case Windows 7 Server)
that lesspy will crash on subprocess. The problem (and the solution) is
described in the following StackOverflow article:
http://stackoverflow.com/questions/20330385/cannot-find-the-file-specifi
ed-when-using-subprocess-calldir-shell-true-in
Merge pull request #1 from allyjweir/master

Correction to solve subprocess issue on Windows.