config wizard: Assume all errors are auth

Assume all errors when trying to connect to the local
database are authentication errors. On a default
Ubuntu 12.10 install with PostgreSQL 9.1 we get:

  FATAL: role "stoq" does not exist.

This patch works that around by ignoring the error,
the user will be created properly later on when
running stoqdbadmin init

Change-Id: Ie913dab0c00b6cfac1fcb1dc61f1ac4e13fe356c
Merge "config wizard: Assume all errors are auth"