Refactor Salt to use external raet

Tom,

I finished the refactor but didn't get to test it running as Salt. So I did not accept the pull request as I am sure something is broken. But in case you wanted to look at it here it is.  I will test tomorrow running in salt.
If you decide to play around with this you will need to

$ pip install raet

Or clone the raet repo 

https://github.com/RaetProtocol/raet.git

and

$ pip install -e raet