prepare_for_invocation

# File railties/lib/rails/generators/base.rb, line 331
        def self.prepare_for_invocation(name, value) #:nodoc:
          return super unless value.is_a?(String) || value.is_a?(Symbol)

          if value && constants = hooks[name]
            value = name if TrueClass === value
            Rails::Generators.find_by_namespace(value, *constants)
          elsif klass = Rails::Generators.find_by_namespace(value)
            klass
          else
            super
          end
        end