SIGKILL can't be called by signal() on Windows

[rpowis]

On Windows, signal() can only be called with SIGABRT, SIGFPE, SIGILL, SIGINT, SIGSEGV, or SIGTERM. A ValueError will be raised in any other case.

https://docs.python.org/2/library/signal.html#signal.signal (python 2)
https://docs.python.org/3/library/signal.html#signal.signal (python 3)

The following occurrences of SIGKILL are therefore breaking service-manager on Windows...

https://github.com/hmrc/service-manager/blob/master/servicemanager/smprocess.py#L16
and
https://github.com/hmrc/service-manager/blob/master/servicemanager/subprocess.py#L1555