feature: Support multiple views

[JessicaMulein]

Leave the current view.json as the default view, support additional views

consider x.view.json and then be reachable on the API as /views/table/x with the excel then being in /views/table/x/excel

other possibility is modifying the view.json structure to support multiple views within it.
Currently view columns are under columns property- but could just as easily be nested under a separate property keyed by the view name with the columns to be queried underneath.

I think I like having fewer files, so extending view.json might be my preferred approach.