Add Docker environment & web demo

[chenxwh]

Hey @onion-liu! 👋

This pull request makes it possible to run your model inside a Docker environment, which makes it easier for other people to run it. We're using an open source tool called Cog to make this process easier.

This also means we can make a web page where other people can try out your model! We have included the face alignment to the input images. View it here: https://replicate.ai/onion-liu/blendgan

Do claim your page here so you can own the page, customise the Example gallery as you like, and push any future update to the web demo. We'll feature it on our website and tweet about it too.

In case you're wondering who I am, I'm from Replicate, where we're trying to make machine learning reproducible. We got frustrated that we couldn't run all the really interesting ML work being done. So, we're going round implementing models we like. 😊