Return Id Property for User in REST API Group's User List Request

[SethLewis1]

Please return the id property for users of a given group in a portal. 

If fetching the users for a given group, the current response is:

 {
      "username": "username1",
      "fullName": "First1 Last1",
      "memberType": "member",
      "thumbnail": null,
      "joined": 1460497506000
    }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Adding the user id value would provide for more effective relationships between user and group objects when using the REST or Python APIs.

User—ArcGIS REST API | ArcGIS for Developers 

{
    "username": "<username>",
    "id": "<user id>",
    "fullName": "<first name> <last name>",
    "availableCredits": <available credits>,
    "assignedCredits": <allocated credits>,
    "firstName": "<first name>",
    "lastName": "<last name>",
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Edited to add additional syntax and revised property name from userId to id