fix some win32 problems when OSFS points to root of a drive
fix some win32 problems when OSFS points to root of a drive

Basically, long-format file names the point to a drive are invalid unless they
end with a backslash.  So "\\\\?\\C:" is wrong (and you'll be told it doesn't
exist) while "\\\\?\\C:\\" is right.


git-svn-id: 74b2def6592cf29d88d1a5d33b5c4a2732d8507c@392 67cdc799-7952-0410-af00-57a81ceafa0f

revolunet/pyfilesystem,pscottdevos/pyfilesystem,alekibango/pyfilesystem,pscottdevos/pyfilesystem,anthonybishopric/pyboxfs,anthonybishopric/pyboxfs,duedil-ltd/pyfilesystem,alekibango/pyfilesystem,simonluijk/pyFilesystem