provision/openstack: put "add volume" in a retry loop

provision/openstack: put "add volume" in a retry loop

Attempted workaround for this issue:

2017-03-23T12:33:20.684 DEBUG:teuthology.misc::sh: openstack --quiet volume show  -f json target217182140122-1
2017-03-23T12:34:22.140 DEBUG:teuthology.misc:{
2017-03-23T12:34:22.146 DEBUG:teuthology.misc:"size": 10,
2017-03-23T12:34:22.146 DEBUG:teuthology.misc:"status": "available",
2017-03-23T12:34:22.146 DEBUG:teuthology.misc:"properties": "ownedby='217.182.143.170'",
2017-03-23T12:34:22.146 DEBUG:teuthology.misc:"user_id": "122b249e82994f5aa8ec6a31b7891df5",
2017-03-23T12:34:22.146 DEBUG:teuthology.misc:"description": null,
2017-03-23T12:34:22.146 DEBUG:teuthology.misc:"availability_zone": "nova",
2017-03-23T12:34:22.146 DEBUG:teuthology.misc:"bootable": "false",
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"encrypted": false,
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"created_at": "2017-03-23T12:33:17.000000",
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"multiattach": false,
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"os-volume-replication:driver_data": null,
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"name": "target217182140122-1",
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"snapshot_id": null,
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"consistencygroup_id": null,
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"replication_status": "disabled",
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"os-vol-tenant-attr:tenant_id": "43583fef7b734bb1b6fb5f86d48abe5e",
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"source_volid": null,
2017-03-23T12:34:22.147 DEBUG:teuthology.misc:"os-volume-replication:extended_status": null,
2017-03-23T12:34:22.148 DEBUG:teuthology.misc:"type": "classic",
2017-03-23T12:34:22.148 DEBUG:teuthology.misc:"id": "e6949180-87fe-4f4c-b0a0-e3ea35bdb2e2",
2017-03-23T12:34:22.148 DEBUG:teuthology.misc:"attachments": []
2017-03-23T12:34:25.036 DEBUG:teuthology.misc:}
2017-03-23T12:34:25.042 DEBUG:teuthology.misc::sh: openstack server add volume target217182140122 target217182140122-1
2017-03-23T12:35:30.536 DEBUG:teuthology.misc:No volume with a name or ID of 'target217182140122-1' exists.
2017-03-23T12:35:34.512 ERROR:teuthology.provision.openstack:Command 'openstack server add volume target217182140122 target217182140122-1' returned non-zero exit status 1

Fixes: http://tracker.ceph.com/issues/17659
Signed-off-by: Nathan Cutler <ncutler@suse.com>