Remove default culture arg to give manifest configuration a chance.

[cstkingkey]

fix #148

[volks73]

@cstkingkey Nice work. The default value in the CLI argument explains why the unit tests were passing and the fn culture implementation looked correct. It probably would have taken me a while to find the cause.

I am going to merge this to resolve the issue, but it would be great to add an integration test that covers this at some point.