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

For example, look at the ".configure_display_manager" describe in this same file. A very similar case. ```Package.InstallAll``` is always called. But it's used in one "it" block as an expectation (with all the parameters and everything, since we are actually stating what do we expect) and it's used in other blocks as a more relaxed "allow" because, even if it's called, is not what that "it" block is about.