Ogr view model

Added an ogrItemViewModel that forwards files to our ogr2ogr service for conversion.
On drag and drop the file is uploaded to the server on a url it is loaded by the server.
Made this the default fall through for formats we don't have explicit handlers for.
Put 1MB size constraints on server and client side
Added airports.zip (shape file) to our init_test.json list

`FormData` isn't supported in everyone's favorite browser: IE9.
https://developer.mozilla.org/en-US/docs/Web/API/FormData

Working around this may be a lot more effort than it's worth, but we should at least inform the user their browser is too old rather than failing.