Add admin order invoice

[pdt256]

As an admin user, I want to be able to print the invoice on my desktop printer so that I can fulfill the order away from the computer. I also want to see an invoice preview.

[pdt256]

Should this be a non-free enterprise level feature?

[pdt256]

This will require a queue processing system. Commands that generate an invoice pdf/jpg will have to be executed by a worker from a job scheduler. The most likely candidate job scheduler/worker manager is Gearman. The most likely candidate pdf/jpg generator is Apache Fop.