Feature request: HTTPS listener

[ColinGilbert]

Hi,

I noticed that the HttpLoadBalancerExtension only support non-secure, port 80 HTTP. It would be great if prior to dropping the alpha designation we could have it also support HTTPS.

The issue was mentioned in the following PR: #303

This should be a priority as it's a relatively easy fix that'll greatly contribute to securing our apps made with these constructs.