auto scale JVM heap size based on dyno size

Yea, that's fine. The problem is that it's already set for 99% of apps (and thus Xmx is already set). I can't unset it because I can't reliably determine if it was set by this, or set intentionally by the user. I want the cases where the user intentionally set it to override my magic. But I want my magic to override those cases where it was set by this file.