Make overwriting / updating vm.args and app.config optional

[adamramage]

Extreme cases require the vm.args and app.config files to not be modified as part of the start up.

change adds an option via envs to disable the script from making such changes. default is to update/modify files.

[chrzaszcz]

Thanks @adamramage for your contribution.

Could you provide more information about the need for this change? The files are updated to keep them in sync with the environment variables, and I would like to know the reasoning behind skipping this step.