Spanish translation updates

Peter,

Attached is a round of spanish translation updates which would take it
to 100% again.

$ for i in bin/initdb bin/pg_ctl bin/pg_config bin/pg_dump bin/psql backend; do echo -n $i": "; LC_ALL=C msgfmt -c -v
$i/po/es.po;done 

bin/initdb: 99 translated messages.
bin/pg_ctl: 96 translated messages.
bin/pg_config: 27 translated messages.
bin/pg_dump: 353 translated messages.
bin/psql: 497 translated messages.
backend: 2147 translated messages.

--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
Major Fambrough: You wish to see the frontier?
John Dunbar: Yes sir, before it's gone.