Allows salt minion to run directly from source on Windows

salt.cloud depends on importing pipes, which isn't present on windows.  It's excluded from the binary distribution, so there's no issue there, but it's annoying having to modify the source to get the scripts to run under windows.

In order to run on Windows directly from the Python scripts (Instead of the binary distribution), I've made the imports to salt.cloud* conditional on the platform.  This prevents me from having to go through the setup process each time I want to test a build, or from having to delete the cloud directory in my working copy to avoid it from being imported.  

I'm not a Python expert, so I may be doing this wrong so am very open to any other ideas.

Thanks in advance for any advice / considerations.