Enhanced upload.html so everyone can specify better field names.

I am actually just half-way done with the implementation: the checkboxes still
need to do something and the new labels should be used. It is nice, however
that it is not a complete unreadable mess.
More work on upload.html

- values are also displayed as a tooltip (just in case they are too long)
- checkboxes disable text input field/value
And yet more work on upload.html

- checkboxes display a tooltip of what they are actually doing.
Finished new upload.html.

It does exactly what it is supposed to do. I also find navigation with tab
pretty efficient.
Replaced some 'attr' with 'props'.