zinid Keep info about carbons inside session table
Accordingly, Mnesia/SQL/Riak table 'carboncopy' is not used anymore
and can be safely removed.

As a consequence, the commit deprecates the following options of
mod_carboncopy:
- ram_db_type
- use_cache
- cache_size
- cache_missed
- cache_life_time

Fixes #2663
Latest commit 109ed8f Dec 1, 2018