Fixing fetch broker information API

[xiangfu0]

Current controller /brokers APIs only returns instance id and expect instance is in the format of ROLE_HOSTNAME_PORT, however this is not the right thing any more.
So we propose the new /broker/v2 APIs which expand the instance id to a json blob with the fields: instanceId/host/port/etc.

Current API:

➜ curl localhost:9000/brokers | jq .
{
  "tenants": {
    "DefaultTenant": [
        "Broker_127.0.0.1_8000"
    ]
  },
  "tables": {
    "airlineStats": [
        "Broker_127.0.0.1_8000"
    ]
  }
}

New API example:

➜ curl localhost:9000/brokers/v2 | jq .
{
  "tenants": {
    "DefaultTenant": [
      {
        "instanceId": "Broker_127.0.0.1_8000",
        "host": "127.0.0.1",
        "port": 8000
      }
    ]
  },
  "tables": {
    "airlineStats": [
      {
        "instanceId": "Broker_127.0.0.1_8000",
        "host": "127.0.0.1",
        "port": 8000
      }
    ]
  }
}

@KKcorps @kishoreg

[KKcorps]

@fx19880617 Should I take this up?

[xiangfu0]

@fx19880617 Should I take this up?

please :)