Basic Chain - In Go

Created by following this great tutorial, and also inspired in part by this existing Go implementation https://github.com/crisadamo/gochain.

Completed for learning purposes. How this differs from the original:

• Proof of Work involves hashing a block's data (transaction data, previous hash) with the brute-force calculated proof, rather than the previous block's and current block's proofs.
• A merkletree is implemented to hash pending transactions, where the merkle root becomes part of block hash calculation.

Stil some refactoring to do at this point.

Setup

Simply run

cd path/to/app
go run cmd/start_node.go --port=<port_num>

to start a node.