Fixed the ubuntu initscript

So i tried to fix the initscript to not use dirty workarounds, as stated in https://github.com/RuudBurger/CouchPotatoServer/issues/1489#issuecomment-14766554

It _should_ work by now, i was a bit confused why you specified the pidfile in the arguments of CouchPotato.py as well, but i don't know how you make a daemon in python, so you will have had a reason for this. ;)