roles/postgres: Create a new postgres_ssl_hosts variable that will be used to determine which hosts can login using ssl

roles/archweb: Memcached service.
roles/postgresql: Initial work on SSL support.

roles/postgres: Added default values to the max_connections and shared_buffers variables.

playbooks/apollo: Added the sudo role and the security_tracker role. Also changes the posgres to include the new variables.
roles/postgres: Merged the new configuration (from 9.6) and added two new variables for making it easier to test the role on a vm/container.

postgres must be able to connect to all databases,
else the postgres_db ansible module is broken.

Signed-off-by: Sven-Hendrik Haase <svenstaro@gmail.com>