Add checks not to overwrite defaultnotify options in the nut-sendmail-notify fashion.
Use lists for defaultnotify instead of option.
Add check not to overwrite notifycmd if already defined.
upssched-cmd script must not be called directly, it is called by the upssched binary with needed arguments.

Signed-off-by: Pascal Coudurier <coudu@wanadoo.fr>

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>