misc/tsuru-setup: changing setup_platforms function call order

The setup right after mongodb startup was throwing an error because
mongo is not starting in a timely fashion, so I delayed the platform
setup script to run to give mongodb some time to wake up
etc/tsuru-docker.conf: removing default index

This would make tsuru push all applications images by default to the
docker public index, which is really no good.

Thanks to @dgryski.