Test to check person older than other

  - Add days between function in the controller.
  - We use days between from joda time to retrieve difference in days.
  - We could compare two people but we need extra logic to compare from name.
  - We will refactor the ArrayList to be a type of Hash based on name
  - We will consider name as a key to be able to compare differece in days from people in O(1) time.