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.
Apparently things start differently with trixie, so modified the system
monitor code to keep trying to allocate the resources it needs (and
adapter and a client to the i2c bus). This mades the code work,
and startup is not affected.
