Create Kill-VM.ps1

Performs kill-vm function written by Alan Renouf. Execution prompts user to choose Hard or Soft kill, then prompts for confirmation. I did not include the Force option as I have never needed it, but a prompt for it could be easily added.
From description of the function:
Users should always attempt 'soft' kills first, which will give the VMX process a chance to shutdown cleanly (like kill or kill -SIGTERM). If that does not work move to 'hard' kills which will shutdown the process immediately (like kill -9 or kill -SIGKILL).
Merge pull request #1 from Mann5112/patch-1

Create Kill-VM.ps1