Assumed battery location on Linux systems

This module, and consequently the battery-life module, do not work on all Linux-based systems due to a hard-coded expectation of the location of the battery in the filesystem (ie. `/org/freedesktop/UPower/devices/`). For instance, my Arch Linux machine uses `/sys/class/power_supply/BAT0/`, although some systems may still use the now deprecated (as of kernel 2.6.24) `/proc` for such information.

Start by inspecting the module and the battery-life module for the hard-coded /org/freedesktop/UPower/devices/ path. Compare the reported UPower path with /sys/class/power_supply/BAT0/ and the deprecated /proc location, then determine the supported discovery behavior and how it should be tested. Done means battery information works across the relevant Linux layouts.

Written by the indexing model from the issue text.