Minor changes to Python test harness to allow it to be used on Windows.  Closes #4366

We have some tests for the Raven framework that we want to run on Windows.  There are a couple of small issues that prevent it from running out of the box with the Windows Python distribution.
This is exactly the problem.  We now have duplicate code.  If someone modifies one of these and not the other then we have a hidden bug.

I like this code better:

```
 if "WINDOWS" in self.harness.checks['platform']:
  print 'What the hell are you doing?  Cut it out!'
  sys.exit(1)
```

:wink: