Update the logback config to inject the application.home property when running the app

[AlexITC]

It would be useful to be able to override the application.home property in the logback.xml settings, let's find a way to do so, and propagate it to the start script.

This allow us to store the logs outside of application directory.

References:

• https://www.playframework.com/documentation/2.8.x/SettingsLogger
• http://logback.qos.ch/manual/configuration.html