Don't disable existing hidden services

At the moment, if tor already runs hidden services, onionshare's `set_options()` disables them.
There's also no attempt to remove onionshare's hs on `cleanup()` (although the "good news" are that even when I try, it doesn't work :wink:. I guess there's something I don't understand about controlling hs via stem).

Another minor change is that now a Ctrl-C during the `wait_for_hs()` (I do that a lot :innocent:), would also trigger `cleanup()`.