Rename /etc/rsyslog.d/10-crowbar-client.conf to 99-crowbar-client.conf

We want this to be the last config file; for instance, this should be
included after 11-swift.conf. Of course, we could rename 11-swift.conf,
but there might be other files.
My point was to avoid having the file resource defined once the file is not there anymore. But maybe it's not worth it?