Refactored the recommendation resource, to add
missing semi-colon and moved the response to be
inside the the `try-catch` statement
Recommendation library added:
- It will search and filter among the user's follows
  listened music tracks and return the ones the user
  has not yet listened.
- If the list length is less than 5, it will then
  will return the filtered unlistened music list
  of global tracks.