[2.1.1] config.resource system property ignored

Setting the _config.resource_ property before starting play does not work, as it's not taken into account. I am setting it to the value "local.conf" but "application.conf" is used instead. 

I have created a small play application to reproduce this.

[Sample application](https://github.com/diegovar/play2.1.1-config-resource-error)