Use primary device for main label

This is a fix for laptop users with more than one battery where the main label would report data for a random battery instead of the battery total.
Merge branch 'patch-1' of https://github.com/zirgon/Cinnamon into zirgon-patch-1

Conflicts:
	files/usr/share/cinnamon/applets/power@cinnamon.org/applet.js