Support webpack dist

[Joelith]

It would be great if the fn cli could support webpack compiled dist files instead of having to send the entire code base and node_modules in with the deployment. Not only would this reduce file size, it would also allow us to add test code that we don't want to submit to the server. For a project I'm working on I have a lot of test scripts and dummy data, many of which are Mbs in size. If I didn't have to have those included it would be great.

I've worked on a patch to fix this and will create a PR shortly.