net/nut: Build optional separate packages and ucify

net/nut: Build optional separate packages and ucify

With a LuCI app (of which I have one written) ucification makes
sense (and is in fact needed), so ucify the initscripts.

Also, rather than making selection of things to include an image
a matter of selecting compile-time config options, make optional
things into seperate packages that are built in default builds,
and leave selection of what to include or not up to the user
(e.g. using ImageBuilder, or adding packages via opkg).

Signed-off-by: Daniel Dickinson <lede@cshore.thecshore.com>