Re: Proposal: knowing detail of config files via SQL

The following review has been posted through the commitfest application:
make installcheck-world: tested, failed
Implements feature: tested, passed
Spec compliant: tested, passed
Documentation: tested, passed

Looks good overall, but make installcheck-world does not pass. rules.sql outputs all system views to pg_file_settings will need to be added:

*** src/src/test/regress/expected/rules.out 2015-04-24 12:11:15.000000000 -0400
--- src/src/test/regress/results/rules.out 2015-04-28 10:44:59.000000000 -0400
***************
*** 1308,1313 ****
--- 1308,1319 ----
c.is_scrollable,
c.creation_time
FROM pg_cursor() c(name, statement, is_holdable, is_binary, is_scrollable, creation_time);
+ pg_file_settings| SELECT a.sourcefile,
+ a.sourceline,
+ a.seqno,
+ a.name,
+ a.setting
+ FROM pg_show_all_file_settings() a(sourcefile, sourceline, seqno, name, setting);
pg_group| SELECT pg_authid.rolname AS groname,
pg_authid.oid AS grosysid,
ARRAY( SELECT pg_auth_members.member