Retrieve all retention policies for a database

Example response

{
  "retentionPolicies": [
    {
      "name": "weekly",
      "duration": "7d",
      "replication": 1,
      "shardDuration": "7d",
      "default": true,
      "links": {
        "self": "/chronograf/v1/sources/1/dbs/NOAA_water_database/rps/liquid"
      }
    }
  ]
}