Call to undefined function commerce_product_type_get_name()

Marked #1875124: Fatal error when enabling the module as duplicate of this

There's no point of using this module without commerce product enabled, so let's add a dependency.

In the dupe thread, it lays out a simple case that both the author and myself ran into: we wanted to use commerce price fields without using commerce products. Commerce Feeds is the natural way to do this.