wrong output of unicode in json

[Vladislav Belogrudov]

Pike release,

when adding description to volume in unicode the operation succeeds and also client reports correct values in table format. But it does not do it in json:

root@operator cinder]# docker-ostk openstack volume show vol1 --format table
+--------------------------------+--------------------------------------------------+
| Field | Value |
+--------------------------------+--------------------------------------------------+
| attachments | [] |
| availability_zone | nova |
| bootable | false |
| consistencygroup_id | None |
| created_at | 2018-01-17T11:08:26.000000 |
| description | myvolume™ |
..

[root@operator cinder]# docker-ostk openstack volume show vol1 --format json
{
  "migration_status": null,
  "attachments": [],
  "availability_zone": "nova",
  "os-vol-host-attr:host": "cinder-cluster-1@zfssa-iscsi#zfssa_iscsi_backend",
  "encrypted": false,
  "updated_at": "2018-01-17T11:14:27.000000",
  "replication_status": null,
  "snapshot_id": null,
  "id": "4a2c4578-7372-4f6f-8a69-7f0e16dfae9f",
  "size": 1,
  "user_id": "a9a863452d674e629d4eae51de2eef33",
  "os-vol-tenant-attr:tenant_id": "efd522eaafc145c1a025d336f84d7b23",
  "type": null,
  "os-vol-mig-status-attr:migstat": null,
  "status": "available",
  "description": "myvolume\u2122",