Exit code does not tell if the service was provided or if it was not
provided due to command line or setup errors.
Change errors to return EXIT_FAILURE instead of 0. Also change other uses
of 0 to EXIT_SUCCESS and 1 to EXIT_FAILURE for clarity and POSIX
conformance.
Signed-off-by: Marko Kohtala <marko.kohtala@gmail.com>
