Generate group_vars samples automagically

Generate group_vars samples automagically

This adds a script, generate_group_vars_sample.sh, that generates
group_vars/*.sample from roles/ceph-*/defaults/main.yml to avoid
discrepancies between the sets of files. It also converts the line
endings in the various main.yml from DOS to Unix, since generating the
samples was spreading the line ending plague around to more files.