Description:

Stubs out a new PDF producer and its views. Pass the producer name, either
CamelCased or under_scored, and an optional list of document names as arguments.
This generates a producer class in app/pdf_producers and invokes your template
engine and test framework generators.

Example:

`rails generate z_pdf:producer Forms invoice receipt`
creates a Forms producer class and views:
    PDF Producer:   app/pdf_producers/forms.rb
    Views:          app/views/forms/invoice.erb
                    app/views/forms/receipt.erb