Use an existing letsencrypt certificate when creating a new deployment

[tjcrone]

I have run into rate limits for letsencrypt certs when debugging/testing new clusters, because kube-lego appears to request a new certificate whenever it is installed. I am wondering if there is any way that we can optionally export (into secrets) an SSL certificate and have hubploy install this certificate in the right place so that kube-lego does not need to request a new one from letsencrypt and go over our limit? Going over the limit is really bad because we may need to wait up to a week to get a new certificate and have a working Pangeo deployment. Any thoughts on this? Happy to help if I can get some direction on how to proceed.