TODO

- Modify the delete shopping list function: search for the shopping list id in all accounts
 and then remove it from all accounts --> looks like an heavy computation, i should probably refactor the whole sharing
 process

- Search friends should not be an API level function. The Android application will
  query the Facebook API using the cached access token. The API should offer a function to share a list, that
  accepts facebook friends user ids as input.
  If these user ids are not yet registered, then I can create a collection that stores documents such as:
  { $facebookUserId: [list of shared list ids] }
  Each time a user is created, we check this collection and we add the list ids into the shoppingLists array of the account.

- How do I keep track of users a list has been shared with, who are not on ShopWithMe yet? I mean, when I fetch
  a shopping list, this user's id won't be into the invitees array because the account has not yet been created!
  Solve the problem about sharing with persons not yet registered: invitees
  contains ObjectIds and for these users we still do not have them as they are not
  yet registered! Maybe I could put the facebook user id into invitees and each time I fetch a list, the client has
  the responsibility to query Facebook for resolving these user ids into name, last name and the profile pic.
  Does Facebook has an API endpoint that given a user id gives back those info?

- Modify test/Routes.js to add a after() method to cleanup db and close connection mongodb