work around OBS not declaring localhost

tests running in the openSUSE Build Service fail with
'Failed to lookup host/port: "localhost:0"' because for whatever
reason /etc/hosts is missing the "localhost" name

https://build.opensuse.org/package/live_build_log?arch=x86_64&package=rubygem-ruby-dbus&project=devel%3Alanguages%3Aruby%3Aextensions&repository=openSUSE_Factory
Releasing version 0.9.1.