Adds additional configuration options for NGINX

I needed to add SSL client authentication and a few other options for an application I'm working on. This adds the ability to specify client auth, as well as any generic directive into the location declaration.
Instead of starting the container w/ `CLIENT_CA_NAME`, could it instead use a naming convention similar to how the SSL cert and keys are defined?  Maybe `<host>.cacrt`.  Then in the template, if that cert exists, client cert verification is setup w/ `ssl_verify_client on`.

Also, can we drop the `SSL_VERIFY_CLIENT` env var and always use `ssl_verify_client on`?