Change old_passwords default to disabled because it breaks current rails
apps that are using the mysql2 gem.

Error is Mysql2::Error: Connection using old (pre-4.1.1) authentication
protocol refused (client option 'secure_auth' enabled)

This occurs on 5.5 servers even though secure_auth is disabled because old_passwords=1 generates the pre-4.1.1 14 char hash rather than the
newer style 31 char hash.