Incorrect response from associating zero or more Federation Resolvers with a Federation

[ocket8888]

This Bug Report affects these Traffic Control components:

• Traffic Ops

Current behavior:

When a Federation has zero or more Federation Resolvers assigned (via /federations/{{ID}}/federation_resolvers) the response is wrapped in an extra response/alerts top-level response object like so:

{
	"alerts": [
		{
			"text": "0 resolver(s) were assigned to the dev. federation",
			"level": "success"
		}
	],
	"response": {
		"response": {
			"replace": false,
			"fedResolverIds": null
		},
		"alerts": null
	}
}

Note that the response object is at response.response instead of just response, and the response object has the extraneous and undocumented "alerts": null property.

The documented example response does not show this strange nesting, so it's probable that this is a regression bug.

Expected behavior:

The response object should match what is documented, and not wrap what is documented under its own response property.

Steps to reproduce:

1. Create a CDN Federation and assign it to your user
2. topost -kp federations/1/federation_resolvers '{}' (assuming the created Federation's ID is 1).