Add instructions and a repository of sample files for getting neighborhoods and analysis results in development

[KlaasH]

The instructions for spinning up a local development instance are decent, but they only get you to the point of having a running instance with no data loaded, and most actual development tasks depend on having at least some data to interact with.

This has come up more than once, most recently in this Slack thread. As noted there, the quickest way to get neighborhoods and jobs is to load a batch file--it will import all the neighborhoods and schedule a job for each of them. But the jobs don't actually run, and there's not currently a good shortcut to getting completed analysis jobs that will show up on the public-site views. It wouldn't be that hard to set something up to facilitate that, though, i.e. by exporting a handful of jobs and making the zipped files available to download and import.

So yeah, we should add instructions for getting set up with sample data, supported by a collection of batch boundary files and exported analysis results (probably in an S3 bucket).