Set ceph key when using manila ceph backend

Set ceph key when using manila ceph backend

Manila ceph driver reads ceph's client configuration
(keyring is the most important) from ceph.conf file
(or any other file set by cephfs_conf_path). ceph.conf
should be updated with keyring location.

If ceph is deployed by tripleo then also manila ceph key
is added into ceph and ceph filesystem is created.

Depends-On: I18436a64fc991b9e697a1d79e369ac110cf8fe20
Change-Id: Iac4a260af6738ed6afd4bcb107221a736d07c1b5
Partial-Bug: #1644784
Closes-Bug: #1646147