bug/output_format param does not work when Accept header is sent

[awalker4]

This returns json:

curl 'http://localhost:8000/general/v0/general' --header 'Accept: application/json' --form files=@sample-docs/layout-parser-paper-fast.pdf --form output_format="text/csv"

And this returns csv:

curl 'http://localhost:8000/general/v0/general' --form files=@sample-docs/layout-parser-paper-fast.pdf --form output_format="text/csv"

I think we want some sort of indication that the Accept header is overriding the output_type, maybe an error when both are present with different filetypes?