* 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.
This adjusts the following:
* Systemd unit dependencies
* Location of docker daemon (/usr/bin/ -> /snap/bin)
* Default data storage location
* Configuration storage location
It allows optionally using both 'jq' and 'docker' from the snaps
provided by the Ubuntu server 18.04 installation process.
