Support multipart/form-data uploads

[pceccato]

Uploadr uploads its file by sending the file data in the payload of a POST request to the upload controller on the server.

I am using it in a corporate environment with IBM Tivoli Access Manager/Webseal, which is a reverse proxy handling authentication between the users browser and the grails application server.

The proxy attempts to decode the payload, but beacuse it is binary data it fails with a 400 bad request error.

If there was an option to upload the file like a standard HTML file upload form with content type 'multipart/form-data' it would work.