Don't HTML-encode formid or version

[lognaturel]

Collect HTML-encodes all unicode for reasons I am unsure of. This is generally ok but it's problematic for formid and version because servers expect an exact match. At the very least, we should pass through formid and version unchanged. There might be a broader question about whether it makes sense to HTML-encode anything but perhaps that's best left for another time if we can find a reasonable way to fix just the formid and version identifiers.

Enketo correctly passes through any unicode in formid or version.

tést.xlsx

[lognaturel]

Users have been running into this with some frequency. Let's at least see what our options are here.

• is the whole submission blob HTML-encoded?

[lognaturel]

We've decided to move forward with building true UTF-8 submissions (matching Enketo). The JR change has gone in (thanks, @seadowg!). We need to incorporate it here and also add the encoding attribute.