Fix if statement for nav class addition
Fix if statement for nav class addition

The nav class should be added when the current depth is 0, meaning when the item is the first to be rendered. The previous way checked if the item had a parent. But this would screw up rendering if the user wanted to render just a subset of the tree.
althaus/bootstrap-bundle,braincrafted/bootstrap-bundle,althaus/bootstrap-bundle,bigfoot90/bootstrap-bundle,althaus/bootstrap-bundle,lashus/bootstrap-bundle,lashus/bootstrap-bundle,bigfoot90/bootstrap-bundle,lashus/bootstrap-bundle,bigfoot90/bootstrap-bundle,braincrafted/bootstrap-bundle,braincrafted/bootstrap-bundle