Implement epic cluster management

[snowch]

Create cluster:

POST /api/v2/cluster/ HTTP/1.1
Host: 127.0.0.1:8080
Content-Length: 336
Accept-Encoding: gzip, deflate
REMOTE_ADDR: 85.255.236.160
Accept: */*
User-Agent: python-requests/2.6.0 CPython/2.7.5 Linux/3.10.0-1127.18.2.el7.x86_64
Connection: keep-alive
X-BDS-SESSION: /api/v2/session/41767072-b4ac-48fb-903b-118437e9490e
Authorization: /api/v2/session/41767072-b4ac-48fb-903b-118437e9490e

{
  "isolated": false,
  "label": {
    "name": "c1",
    "description": ""
  },
  "dependent_nodegroups": [],
  "debug": false,
  "two_phase_delete": false,
  "nodegroup": {
    "role_configs": [
      {
        "node_count": 1,
        "flavor": "/api/v1/flavor/1",
        "role_id": "utility"
      }
    ],
    "catalog_entry_distro_id": "bluedata/centos6",
    "config_choice_selections": [],
    "constraints": []
  }
}
HTTP/1.1 201 Created
Access-Control-Allow-Origin: *
Content-Length: 13
Content-Type: text/plain
Date: Fri, 31 Jul 2020 03:48:28 GMT
Location: /api/v2/cluster/1
Server: HPE Ezmeral Container Platform 5.1

201 Created