Multiple files uploader

[rgaudin]

This is where most of the UI happens. It needs to be on a dedicated page.

• gets a unique session ID from server ; attached to user-id
• file size limitation (individual and overall) enforced on client and server
• UI reports async status for each file: uploading (with progress), processing, refused, OK
• Bytes written (on receive) are compared against session limit
• Session gets an expiration date as soon as we receive a first file.
• Files uploaded are immediately uploaded to S3 if session accepts it (overall filesizes ok)
• Uploaded filename is computed from filehash and session ID, hashed with a user-specific salt

[rgaudin]

Done