Versioned RethinkDB schema administration

[martijn-benjamin]

Add a tool that will create/update database/tables/indexes definitions on server startup

We can use something like this, although i'm not sure if this also runs any updates, new indexes/tables etc.

The goal is that we have versioned administration of the RethinkDB schema trough the used tool.

https://www.npmjs.com/package/rethinkdb-init

There are probably more tools out there for this purpose, let's make a shortlist first.