Native power notification daemon

[hanaral]

Problem

The gnome power statistics notifications are categorised as 'Other', have no settings to change when low battery warnings for the laptop or peripherals and whether they are sent at all. This means users have to disallow all 'other' notifications, or put up with being visually/audibly spammed by a critical notifications.

Example with my Apple Magic Keyboard which runs on AA batteries:

Proposal

The notifications gnome-power stats provide should be disabled entirely and replaced with a native power-reporting-daemon which has some saner defaults, provides useful notifications and can have its settings changed from this plug.

[hanaral]

Another example of poor support (possibly 0 amount of sanity checking):

[danirabbit]

I had started working on sending power notifications in the power indicator since we're monitoring battery levels there already: elementary/panel-power#229