Add init scripts and docs for Upstart and OpenRC

Expanding on @aitorpazos earlier commit of a systemd service file, here are some additional scripts and documentation updates to support Upstart and OpenRC.  Tested on Gentoo/OpenRC 0.12.4 and Ubuntu trusty/Upstart 1.12.1. 
I mean, it's saying "set the rpcuser and rpcpassword". It should be clarified that it's not an rpcuser and rpcpassword that you should be *using*. And yeah, it's probably a good idea to fix that somehow -- maybe with a wrapper script or something?