Fixed an issue with a trailing slash on Windows

On Windows, given the following configuration, the update would fail:

{
  "type"     : "local",
  "local"    : "c:\\test\\test.txt",
  "remote"   : "d:\\example"
}

It would try to execute the following commandline:

xcopy /y /e /h c:\temp\test.txt d:\example/\

This is due to a trailing slash on the remoteFile variable which wasn't
getting removed. The fix is to remove any trailing slashes on the
remoteFile variable. This is safe to do, because we always append our own
trailing backslash.
Windows: Stop empty directories from being copied

Changed the xcopy switch from /e to /s. This prevents empty directories
from being copied. This is especially important if you are copying just a
single file. When you copy a single file with the /e flag, xcopy will
also create the entire directory structure even from directories that are
not related to the file you are copying. This takes extra time, and
probably isn't what you would expect to happen.
Merge pull request #3 from jan11011977/master

Fixed an issue with a trailing slash on Windows + Stop empty directories from being copied