Add support to change the shutdown threshold.

The default value for shutdown is less than 5% of battery life left.
Once the system hits this value (or the one specified by the user) the
system will shutdown.

The soc_shutdown value can be changed to 0 to disable this feature, just
realise that the system will lose power and unsafely shutdown.

Also added install and remove functionality.

battery/remove

@@ -1 +1,7 @@
+#!/bin/bash
 sudo rmmod oneUpPower
+sudo rm -vf /lib/modules/`uname -r`/kernel/drivers/power/supply/oneUpPower.ko
+sudo sh -c "sed -i '/oneUpPower/d' /etc/modules"
+sudo rm -vf /etc/modprobe.d/oneUpPower.conf
+sudo depmod -a
+sync