Ability to check Postgres version through psql instead of scanning PG_VERSION

[avinashvallarapu]

Scan Postgres version using psql.

This will eventually help extending the tool to DBaaS platforms like AWS RDS/Aurora, Azure Database for PostgreSQL and Google Cloud SQL for PostgreSQL.

psql -c "select name, setting from pg_settings where name IN ('server_version');

[darold]

This check of PG_VERSION files is part of the CIS Benchmark to check that the PGDATA is correctly initialized but I agree that it is useless in a context of a running server. PostgreSQL won't start if PG_VERSION files don't match. I will consider changing this behavior in next release.

[darold]

Now that we have the infrastructure to exclude some check from the report, best it to define which checks must be removed from the report to be able to run on cloud platforms.