title: How do I use the ExitCode on the TFS InvokeProcess activity?
body: <p>In TFS build I call to a nant script using a custom activity InvokeProcess (we use NANT till we will be able to move to "TFS language")
  I want to fail the build if NANT fails. I guess I should use the Result property of the InvokeProcess.
  How I do that?
  Thanks</p>