VMM/config: Extended configuration check and raise only a ConfigError.
Added new settings 'module', 'port', and 'sslmode' to the database section.
# All parameters are described in pgsql_table(5) / PGSQL PARAMETERS
#
# The hosts that Postfix will try to connect to and query from.
hosts = localhost
# The user name and password to log into the pgsql server.
user = postfix
password = some_password
# The database name on the servers.
dbname = mailsys
# The SQL query template used to search the database
query = SELECT uid FROM postfix_uid WHERE address='%s'