Thanks to @cloudnull great patch at
https://github.com/ansible/ansible/pull/12555
we now have the ability to add more configuration options instead of
having to push a PR to add a new option to the template. So you can
dynamically add and remove flags.
To use it, edit `ceph_conf_overrides` in `group_vars/all` like so:
```
ceph_conf_overrides
global:
foo: 12345
bar: 6789
```
Signed-off-by: Sébastien Han <seb@redhat.com>