Pass parameters to a scenario

[cowboyd]

While the baseline for data generation should be zero-config, we need to be able to constrain a scenario based on certain parameters. Because multiple simulators may respond to a single scenario, parameters should be partitioned based on which simulator they are for. E.g.

{
  person: {
    name: "Bob"
  },
  auth0: false //user is not a member of auth0
}