Allow users to specify overrides in the CephCluster CRD. The override
ConfigMap still exists for emergency situations and is mounted into
daemon pods directly instead of being merged into a Rook-created config
file.

Rook Ceph no longer uses a config file for managing daemons with the
exception of the OSDs which still generate a config in an init
container.
Signed-off-by: Blaine Gardner <blaine.gardner@suse.com>