Using without custom domain

[kcjl519]

Hi,

First of all, thank you for making this project open source, saved me a lot of work trying to do this myself!

I have managed to generate a gallery with thumbsup, and I'm now trying to set up authentication with cognito + lambda. Looking at this repository, as part of the initial configuration, a custom domain is required. Is it possible to set this up without a domain? e.g. just fall back to the cloudfront domain ?