Show how a reload is triggered when it's not needed.

In order to avoid unnecessary reloading of the yaml configuration. The time used to detect the last change to the config file is changed from `change` which is the time of the last file status change to the `modification` time wich is the time of the last data modification.

For more information also checkou http://lunarmodules.github.io/luafilesystem/manual.html#reference and https://linux.die.net/man/2/stat

Fixes: apache#9051

…eloads