`restify.clj`: list-all-in-collection route now supports query string params `format=csv|json` and `filename=foo`
* specifying a `format` will change output format (supported: `csv` or `json`; defaults to `json` if omitted)
* specifying a `filename` will force a `Content-Disposition: attachment` header
Adds a 400 Bad Request status code for invalid output formats
Asana #16567813520843
When building CSV, show sub-columns containing data from first array element.
This is a balance - we can't easily show every array element's values, but we are often working with cases where there are either 0 or 1 elements in the array, in which case it's useful to have this data in the output
Merge branch 'feature/collection-get-csv' into develop