Discussed with: Shawn Webb

pkgng isn't there yet.

This was leaking spurious json output sometimes, confusing
the firmware pages and its users.

Discussed with: ad@

Shell access is sufficient, I see absolutely no value in this.

(configd) flush script output to tempfile to avoid the use of subprocess.check_output which can be slow on some platforms.

refuses to take /usr/local/bin into account, which kind of defeats
the purpose of using the portable "env" command...