Big update on cloud structure.

1. From now on each new user  receive index number. First registered
user is 1, second is 2 and so on.
2. Pick2RandomUsers now much faster (now inside functions, will extract
later).
3. Cloud function "like" now have protection from  using from
non-reviewers. Sends push to new reviewers, adds new reviewers. Now have
_synchronous_  queries run simultaneously- much faster.