service.is_running and require.service

service.is_running doesn't play well with upstart services as the
`service` command returns successfully no mater if the service is
running or not. This updates the functions in require.service to take an
optional paramter that gets passed on to service.is_running to indicate
that the service is an upstart service and checks the output of
`service` to determine if the service is actually running rather than
relying on the exit code.