Provide a way to control Windows service state

[glumpo]

I faced with the need to dissallow stopping my service in some cases, but now it`s impossible to modify list of accepted controls. So here is some changes to provide a way to handle extra controls (like AcceptNetBindChange) and modify list of accepted controls in runtime.

We let user provide windows-specific option with handler which can process ChangeRequest and chanel to notify about accepts changes.