Allow NPM to rediscover a node entirely without re-adding.

Hi,

Here is what's going on:

- Take a Windows Server 2008 R2 box

- Do an in-place upgrade to Windows Server 2012

- Look at NPM, you will notice it still reports Windows Server 2008 R2. No matter how many times you poll the node, the OS will not update.

This is annoying since I've had to re-add all the nodes recently upgraded. There seems to be no trigger to poll the OS type/version and needs to be fixed.

FYI service packs update build numbers as well...