Update clamav app to use native container-to-container TLS

[rahearn]

Just wanted to let you all know that there's been an update to the ajilaag/clamav-rest image that allows it to utilize port 61443 for TLS communication. That would let you remove the code that skips verifying the certificate for that communication.

If you want to use it, we also put together the whole thing in a terraform module, which would let you get rid of the separate repo for the clamav app. More info on that is here: https://github.com/18F/terraform-cloudgov#clamav