Fix Translate module and add related specs

[stephannv]

Add tests to fix implemented here: #101

And replicate behavior for Translate module.

I think Translate module should have a t alias to translate method, so we can have only one module related to translation. But I just followed the current module organization and replicated the behavior.

[stephannv]

This test should fail even when the issue is fixed because allow(I18n).to receive(:translate).with("temp.translation_key") , we do not know what is the prefix before ".translation_key" because we are using a temp class without path.
But the error will be different.

[stephannv]

@joeldrapper I added some specs in this old PR and fixed Translate module to use translation path too.