pgsql: Refine rules for altering publication owner

Refine rules for altering publication owner

Previously, the new owner had to be a superuser. The new rules are more
refined similar to other objects.

Reviewed-by: Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/4cfc9484d4effb0a3aa2c8742bdef0c2bc7a3ca5

Modified Files
--------------
doc/src/sgml/ref/alter_publication.sgml | 7 +++++--
src/backend/commands/publicationcmds.c | 34 ++++++++++++++++++++++---------
src/test/regress/expected/publication.out | 8 ++++++++
src/test/regress/sql/publication.sql | 4 ++++
4 files changed, 41 insertions(+), 12 deletions(-)