Remove pubsub and replace w/ polling head of chain (#122)

* Rename geth package structs to not be prefaced with package name

* No longer need to dump schema since Travis uses migrate

* Rearrange history package

* Removed double request for receipt from block rewards

* Remove Listener + Observers and Replace w/ Polling Head

* Potential Short term Issue w/ Infura (ignore these tests for now)

pkg/geth/blockchain.go

@@ -0,0 +1,63 @@
+package geth
+
+import (
+	"math/big"
+
+	"github.com/8thlight/vulcanizedb/pkg/core"
+	"github.com/8thlight/vulcanizedb/pkg/geth/node"
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/rpc"
+	"golang.org/x/net/context"
+)
+
+type Blockchain struct {
+	client              *ethclient.Client
+	readGethHeaders     chan *types.Header
+	outputBlocks        chan core.Block
+	newHeadSubscription ethereum.Subscription
+	node                core.Node
+}
+
+func NewBlockchain(ipcPath string) *Blockchain {
+	blockchain := Blockchain{}
+	rpcClient, _ := rpc.Dial(ipcPath)
+	client := ethclient.NewClient(rpcClient)
+	blockchain.node = node.Retrieve(rpcClient)
+	blockchain.client = client
+	return &blockchain
+}
+
+func (blockchain *Blockchain) GetLogs(contract core.Contract, startingBlockNumber *big.Int, endingBlockNumber *big.Int) ([]core.Log, error) {
+	if endingBlockNumber == nil {
+		endingBlockNumber = startingBlockNumber
+	}
+	contractAddress := common.HexToAddress(contract.Hash)
+	fc := ethereum.FilterQuery{
+		FromBlock: startingBlockNumber,
+		ToBlock:   endingBlockNumber,
+		Addresses: []common.Address{contractAddress},
+	}
+	gethLogs, err := blockchain.client.FilterLogs(context.Background(), fc)
+	if err != nil {
+		return []core.Log{}, err
+	}
+	logs := GethLogsToCoreLogs(gethLogs)
+	return logs, nil
+}
+
+func (blockchain *Blockchain) Node() core.Node {
+	return blockchain.node
+}
+
+func (blockchain *Blockchain) GetBlockByNumber(blockNumber int64) core.Block {
+	gethBlock, _ := blockchain.client.BlockByNumber(context.Background(), big.NewInt(blockNumber))
+	return ToCoreBlock(gethBlock, blockchain.client)
+}
+
+func (blockchain *Blockchain) LastBlock() *big.Int {
+	block, _ := blockchain.client.HeaderByNumber(context.Background(), nil)
+	return block.Number
+}