Bump to postgres 9.3

Was running into some `pg_dump` incompatibilities between 9.2 and 9.3 so this brings our boxen postgres up to 9.3.2 on the 3.0.1 boxen tag.

If you need to migrate any data, you'll want to take a look at this https://github.com/boxen/puppet-postgresql/issues/22#issuecomment-20571290. 

If you get a failed boxen run due to missing `initdb`, run boxen again so it can pick up on the new binary.

cc @articulate/engineering