Document Record Endpoints, Document file v2

[edcohen08]

Add in the Document Record endpoints for updated the other data around document summaries, e.g. the notes.

Update file handling in document summary to be more user friendly (only require a list of file names, validate the mimetypes against what welkin accepts)

[samamorgan]

I'd like to do some experimentation with this endpoint as well to see what else might be allowed. Ideally, we wouldn't have to have in-memory files, but could stream files instead.