Move start-confluent.sh logic to init scripts

[alexlod]

Currently all Confluent-related services are started via start-confluent.sh, which is installed in /vagrant/configfiles/start-confluent.sh.

This logic should be moved into one or many init scripts.

Without init scripts, all Confluent services aren't started automatically when the VM boots. Instead, they need to be started manually by running: bash /vagrant/configfiles/start-confluent.sh.