Update BlockChain to record NodeInfo (#95)

pkg/core/blockchain.go

@@ -4,6 +4,7 @@ import "math/big"
 
 type Blockchain interface {
 	GetBlockByNumber(blockNumber int64) Block
+	Node() Node
 	SubscribeToBlocks(blocks chan Block)
 	StartListening()
 	StopListening()

pkg/core/node_info.go

@@ -0,0 +1,6 @@
+package core
+
+type Node struct {
+	GenesisBlock string
+	NetworkId    float64
+}