def can_unblock?(friendable)
      blocked? && self.blocker_id == friendable.id && friendable.class.to_s == Amistad.friend_model
    end
def can_unblock?(friendable)
      blocked? && self.blocker_id == friendable.id && friendable.class.to_s == Amistad.friend_model
    end
returns true if a friendship can be unblocked by given friendable