add an "inline" query parameter to tempurl

Giving the inline query parameter will cause the tempurl
response to be given a "Content-Disposition: inline" header,
regardless of other query parameters or metadata. This allows
easy in-line viewing, eg in browsers.

DocImpact

Change-Id: Icd5c544d6a749d4f58e8a921968f4e432a2185db
Merge "add an "inline" query parameter to tempurl"