Make is_local_addr accept localhost.

This is useful for minimal installs where the proxy lives on the same
host as the app.
install-reddit: Add HTTPS to the default install.

This is primarily to show how to set up reddit with HTTPS as well as to
make it possible to test HTTPS content. The default installation uses
the snakeoil cert and is therefore unauthenticated. A properly signed
certificate must be used for actual security.