Add aws config

[scottyhq]

closes #120, I'll be pleasantly surprised if this works on the first try

[scottyhq]

@jhamman and @TomAugspurger - I'm ready to merge this. I've deployed and tested locally and after some trail and error things seem to be working (https://staging.aws-uswest2-binder.pangeo.io/)!! Main changes that will also affect the Google binder:

• bumped dind to 19.03.5 to match binderhub chart default
  https://github.com/jupyterhub/binderhub/blob/089702b32dc0689ba432504724d82bb42ad2a94f/helm-chart/binderhub/values.yaml#L152

• updated dask-gateway tolerations to match pangeo-cloud-federation

I could not get kube-lego to work, so I've moved the aws deployment to certmanager. You might want to do the same with google deployment, maybe not. Instructions in k8s-aws/readme.md
#127

I'll copy the current binder url to prod.yml files after we test this a bit more in a separate PR.