POST /auth/token

Exchange credentials for access token

Header	Value
`Authorization`	`Bearer [token]`
`Content-type`	`application/json`

The request body must be a JSON string with the following fields:

Field	Description
`client_id`	identifies the client. Currently, must be either `node-red-admin` or `node-red-editor`.
`grant_type`	must be `password`
`scope`	a space-separated list of permissions being requested. Currently, must be either `*` or `read`.
`username`	the username to authenticate
`password`	the password to authenticate

Status Code	Reason	Response
`200`	Success	See example response body
`401`	Not authorized	none

{
  "access_token": "A_SECRET_TOKEN",
  "expires_in":604800,
  "token_type": "Bearer"
}