Update rasp pi build script to use our new docker tag system.
Update rasp pi build script to use our new docker tag system.

latest will now point to latest released version of faucet rather than
faucet@master on git.

REANNZ/faucet,shivarammysore/faucet,gizmoguy/faucet,trentindav/faucet,wackerly/faucet,trentindav/faucet,mwutzke/faucet,wackerly/faucet,anarkiwi/faucet,mwutzke/faucet,trungdtbk/faucet,REANNZ/faucet,gizmoguy/faucet,faucetsdn/faucet,trungdtbk/faucet,faucetsdn/faucet,shivarammysore/faucet,anarkiwi/faucet