#180 support for shared database hosting with limited permissions

[arekm]

Please add support for working in limited priviledges shared hosting environment described in:

https://wiki.postgresql.org/wiki/Shared_Database_Hosting

where such rights are revoked from public:

"psql -U postgres template1 -f - << EOT

REVOKE ALL ON pg_user FROM public;
REVOKE ALL ON pg_roles FROM public;
REVOKE ALL ON pg_group FROM public;
REVOKE ALL ON pg_authid FROM public;
REVOKE ALL ON pg_auth_members FROM public;

REVOKE ALL ON pg_database FROM public;
REVOKE ALL ON pg_tablespace FROM public;
REVOKE ALL ON pg_settings FROM public;"