Adds curl command to CLI

- The following are examples of usage:

  $ uaac curl /Users/abc-123

  GET http://uaa.example.com/Users/abc-123

  200 OK
  RESPONSE BODY:
  {
    "id": "abc-123",
    "meta": {
      "version": 0,
      ...

  $ uaac curl -X PUT -d '{"active": false}' /Users/xyz-789

  PUT http://uaa.a1.cf-app.com/Users/00005835-0a04-4a7b-bc26-f0318d7db68c
  REQUEST BODY: "{ "active": false }"

  403 Forbidden
  RESPONSE BODY:
  {
    "error": "access_denied",
    "error_description": "Access is denied"
  }

[#74077516]