Use "-s $APPLICATION_HOME/config.php" instead of "$APPLICATION_HOME" for config persistency

[x86dev]

When using an external data volume, it's a better practice to check for a non-zero and existing config.php instead of the data directory itself:

if [[ ! -s "$APPLICATION_HOME/config.php" ]]; then

This way it's much more obvious when the configuration will be reset and why.

[sakrai]

Thank you for your comments, I will keep that in mind when the next tasks are planned.