Revert "Do not half-close the session socket when communicating with Node.js."

This reverts commit 8f649f075effb61215510810e7d7edcaa428cd9a.
The changes are no longer necessary now that we've overhauled Node.js support.
Prevent Apache from setting the httpd/unix-directory Content-Type,
in case the application doesn't explicitly set a Content-Type.

Closes GH-1197.