Restore full taskd job error details to logging.

This was first "fixed" in de961e2, but then in 8e3c5c3 a better fix
was made so that errormiddleware didn't get applied to tasks, thus
causing the logging to be incomplete.
Revert "[#5326] avoid "Broken pipe" error we were seeing, by providing ErrorMiddleware with an explicit wsgi.errors stream"

Taskd doesn't use errormiddleware since 8e3c5c3

This reverts commit 7eb795608877f0b358aa5234b08dcaccabdee0f8.

Conflicts:
	Allura/allura/command/taskd.py