Setting PDF/A profile over Request Parameter

[messatsuu]

Hey, great project!

I recently had the use-case that I needed to pass the PDF/A Profile via a Request Parameter. I quickly made a Fork and was wondering if this could be of any use in this Project? Recently tested it and it seems to work.

Also would be if someone could go over my changes and see if I've gotten anything wrong, since this was the first time I'm using Scala : )

Diff from Fork.

Thank you!