Configuration of remote administration has been fixed to reload/restart services and/or warn user if necessary

- bnc#893606
- According to the bugreport, Yast Runlevel just restarts display manager while it enables remote administration
- I've fixed the behavior in a way that it starts or reloads services as much as possible and if the display manager is already running, Yast warns user to restart it manually or log out and log in again
- Includes a  nice test case

I feel the difference between `allow` and `expect` a bit unclear.

- `expect` ensures that to code has been called
- `allow` doesn't care whether the code was called or not

I prefer `expect` in such cases, but if you really want it, I can change it to `allow` ;)