* use separate variable to specify Docker config location
* use templates and always adjust paths
This prepares for further customization of file locations.
* allow to customize prefix and sysconfdir
Follow GNU directory variable names and allow to specify PREFIX (by
default /usr) and sysconfdir (by default /etc). This allows to install
hassio scripts and service to alternative locations.
* Warn the user about NOT deleting containers
As the `supervisor` does not support creating the homeassistant container if accidentally deleted, let's warn the users before it's too late and perhaps give a bare minimum of possible ways to recover.
* Update README.md
