pgsql: Rename ident authentication over local connections to peer

Rename ident authentication over local connections to peer

This removes an overloading of two authentication options where
one is very secure (peer) and one is often insecure (ident). Peer
is also the name used in libpq from 9.1 to specify the same type
of authentication.

Also make initdb select peer for local connections when ident is
chosen, and ident for TCP connections when peer is chosen.

ident keyword in pg_hba.conf is still accepted and maps to peer
authentication.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/6f9192df61e183826211ad2eaf325c6de5cf3656

Modified Files
--------------
doc/src/sgml/client-auth.sgml | 96 +++++++++++++++++++----------
doc/src/sgml/runtime.sgml | 2 +-
src/backend/libpq/auth.c | 112 ++++++++++++++--------------------
src/backend/libpq/hba.c | 24 +++++++-
src/backend/libpq/pg_hba.conf.sample | 4 +-
src/bin/initdb/initdb.c | 19 ++++++
src/include/libpq/hba.h | 3 +-
7 files changed, 156 insertions(+), 104 deletions(-)