when enable ceph_nfs,it deploy failed, because no ganesha config
file, and the 'ganesha.nfs' command need root privilege to run.
i will modify ceph_nfs dockerfile,please review. thanks
https://review.openstack.org/#/c/630510/
Change-Id: I347107bc33733061ad043bffe38ecc1d16770afc
Closes-Bug: #1811581