postgres admin.sql fixes

The postgresql/admin.sql that ships in current Debian stable unfortunately does not work: psql does not accept the comment syntax used, host/domain names in roles or database names in columns for GRANT statements. The attached patch below fixes this. There may still be problems with missing GRANTs for the sequences, I'll recheck those tomorrow. This might of course all be fixes in the current sourcetree, in which case I apologize for the noise. Wichert.