TestProcess updates for rendering text with a Proc

I'm just trying to get people aware of my new patch. It's a very
simple update to TestProcess that allows testing of streaming output.
Before my patch TestProcess tries to build an HTML::Document with the
Proc instead of the captured output of the Proc. I've put this
together against tags/, but I'm willing to rework it should
someone recommend I do it on a different branch.


I decided to write up a bit more of a description: