Deno support

[nestarz]

Hi !

Thanks for your amazing work. I'm working on Deno and would love to see this project compatible with this runtime, so I made the required changes so it can works on Deno for whom want use it or to learn from it to make natively supported.

https://github.com/nestarz/postgraphile-deno

[benjie]

How would I go about applying these changes to this repo? Perhaps you could raise a PR?