Added rjil::system::accounts

The class rjil::system::accounts does below stuffs.

1. set root user password (this may be required to login to the
        system from direct console if anything else working)
2. Add all active users
  2a. All user details like ssh keys and passwords are added to
      secrets.yaml
  2b. acive_users hiera array element, which can use to override
      active users in various hierarchies like
      per environment, per role, per node etc
3. Provide sudo access to sudo users
   Effective sudo users are always subset of acitive_users

Added hiera override named secrets. I kept fake secrets like
passwords, and user details for now

Updated Puppetfile to update stdlib to 4.3.2, it has intersection
which rjil::system::accounts code use.