Add support for backends that require SSL

[cin]

There are a lot of different ways to handle this. One way is to setup an external nginx deployment that handles SSL, but this will introduce another hop. In order to eliminate the hop and not have to jump through hoops in VCL to find nginx pods that are colocated with varnish pods, we should consider adding a nginx sidecar so we can talk over localhost for this. It'd simplify config and hopefully allow us to support SSL by flipping a switch.