Add support for PRE_SHUTDOWN service control event

Reworks the existing code to use RegisterServiceCtrlHandlerExW instead of the
older RegisterServiceCtrlHandlerW function. This allows handlers to then receive
the new extended control signals such as PRE_SHUTDOWN which allows for blocking
of the shutdown process for long cleanups on versions of Windows above Win2k3.

The assembly code for amd64 and 386 has been modified to suppor the different
call signature of the RegisterServiceCtrlHandlerExW procedure and the handler
modified to comply with the extended callback/handler call signature required
by the new procedure.

For more info on RegisterServiceCtrlHandlerExW see the MSDN documentation here:
http://msdn.microsoft.com/en-gb/library/windows/desktop/ms685058.aspx
Change all import paths to match repository URL