Allow users to upload images of documents to be translated

[dahoo]

It's possible wih HTML5 (tested on my Andoid 6) with:
<input type="file" accept="image/*" capture="camera">
The fallback is a normal file input.

We should allow the user to censor personal information.
It would also be nice to process the image like e.g. Camscanner does (maybe better in backend).