moved non-protocol, non-network, non-blockchain classes to common folder...

Fixes #22 

As the understanding of how the code base interacts there will be adjustments in subsequent cards. I have taken the code as far as I am willing to adjust for the sake of clean code until I solidify my understanding some items and how they can/should be used moving forward.

Items like "Block" and "Transaction" are both Messages and items stored in the actual BlockChain. Their locations on disk for development does not adequate convey their use. 

I am going to close this issue at this time but will be working to solve how to handle messages that are also non-transient items that are stored in the blockchain.