client configuration should not require ceph.client.admin.keyring

[fultonj]

When using ceph-ansible's ability to configure a ceph client to talk to an external ceph cluster the task fails with the following message:

2017-09-01 20:44:46,615 p=1728 u=mistral | fatal: [192.168.24.10]: FAILED! => {"changed": false, "failed": true, "msg": "Unable to find '/tmp/file-mistral-actiongUI08a/bddc7e56-8f09-11e7-a223-003da9b9b610/etc/ceph/ceph.client.admin.keyring' in expected paths."}

This task should be skipped in that scenario because it's not necessary for the client to have the admin key.

[fultonj]

In addition, if the client admin key isn't copied, it shouldn't be used to try to ceph auth import the created client key and it is not necessary to verify the key either.