Auto generate an FSID

It has becomes really anoying to manually generate an fsid prior to the
inital bootstrap. This commit introduces a method that auto-generates an
fsid. If for whatever reasons you want to force your own fsid you can
simply edit these 3 files and override the fsid variable:

- roles/ceph-common/vars/main.yml
- roles/ceph-mon/vars/main.yml
- roles/ceph-osd/vars/main.yml

Signed-off-by: Sébastien Han <sebastien.han@enovance.com>
Merge pull request #147 from leseb/autogen-fsid

Auto generate an FSID
Fix autogen UUID and add auto gen monitor key

This fixes the UUID auto generation and introduces the monitor key auto
generation.

Signed-off-by: Sébastien Han <sebastien.han@enovance.com>
Merge pull request #149 from leseb/autogen-mon-secret

Fix autogen UUID and add auto gen monitor key
Merge pull request #8 from ceph/master

Rebase from upstream