Content-Disposition header for binary downloads

Currently every binary download response has the `Content-Disposition` header set to attachment, forcing the browser to download the file when linked directly. Some times it makes more sense to let the file be viewed directly in the browser.

Here are some suggestions:
* Remove the header and use the download attribute of the `` tag to make the browser download the link (https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#Attributes). This does not work cross-origin.
* Make the header inline for some hard coded content types (what you suggested)
* Make the headers somehow configurable - for some projects it makes sense to download a pdf file, for others it makes more sense to have it inline.

Start with the issue's three proposed approaches and review the five-comment discussion to determine which behavior is intended for binary download responses. Done means an agreed Content-Disposition behavior is implemented and its browser, cross-origin, and configurability expectations are verified.

Written by the indexing model from the issue text.