Add Debian-style initscript

* Add validators and validation_quorum from the v0.16 release notes.
* We keep having to tell people to do this during integration, let's just make it the default.
* Add comment about the log file location that states that it has to be absolute rather than relative after an integration troubleshoot earlier today.

Signed-off-by: Bryce Lynch <bryce@ripple.com>