This commit standardizes the various todos around the code a bit in a manner recognized by LDoc.
Besides drawing more attention by being displayed in the developer docs, they're also extractable with LDoc on the command line:
```sh
ldoc --tags todo,fixme *.lua
```
However, whether that particular usage offers any advantage over other search tools is questionable at best.
* and some random beautification
* Use getCapacityHW() to ensure latest battery capacity can be retrieved
* BackgroundRunner
* Start background_runner_spec.lua
* AutofrontLight plugin now uses BackgroundRunner plugin
