I'm currently learning a lot about UPSes and the european power grid.

Example: Linepower is: 230 V ± 23 V with a frequency of 50 Hz ± 0,2 Hz

I didn't know the range was that big.

And of UPS batteries rated for 12 voltes, it's comepletely fine to reach
14 volts when fully charged.

This patch adjusts the helm chart to become more standardised. It uses
helm unittest to valdiate changes as well as implementing a
serviceaccount as best practice. It also goes back to all the default
helm helpers for labels, names etc.

Currently the UPS of the cluster is not really monitored, therefore this
patch adds nut-exporter to integrate the UPS status in the regular
prometheus metrics. This should allow to create fancy dashboards and a
calculate the power usage of the infrastructure.

This patch adjusts the tmp volume to be from type emtpyDir with medium
Memory be default, this will use more memory in the container, but
should provide an easier default for users.

Further it also introduces the tmp volume to the web containers, that
require it, in order to process media that is uploaded by users.

It's actually possible to use emptyDir, but only with the correct medium
therefore this new release adjust the documentation in values.yaml