Redo coordinator structure, connect API to node

- API:
	- Modify the constructor so that hardcoded rollup constants don't need
	  to be passed (introduce a `Config` and use `configAPI` internally)
- Common:
	- Update rollup constants with proper *big.Int when required
	- Add BidCoordinator and Slot structs used by the HistoryDB and
	  Synchronizer.
	- Add helper methods to AuctionConstants
	- AuctionVariables: Add column `DefaultSlotSetBidSlotNum` (in the SQL
	  table: `default_slot_set_bid_slot_num`), which indicates at which
	  slotNum does the `DefaultSlotSetBid` specified starts applying.
- Config:
	- Move coordinator exclusive configuration from the node config to the
	  coordinator config
- Coordinator:
	- Reorganize the code towards having the goroutines started and stopped
	  from the coordinator itself instead of the node.
	- Remove all stop and stopped channels, and use context.Context and
	  sync.WaitGroup instead.
	- Remove BatchInfo setters and assing variables directly
	- In ServerProof and ServerProofPool use context instead stop channel.
	- Use message passing to notify the coordinator about sync updates and
	  reorgs
	- Introduce the Pipeline, which can be started and stopped by the
	  Coordinator
	- Introduce the TxManager, which manages ethereum transactions (the
	  TxManager is also in charge of making the forge call to the rollup
	  smart contract).  The TxManager keeps ethereum transactions and:
	  	1. Waits for the transaction to be accepted
		2. Waits for the transaction to be confirmed for N blocks
	- In forge logic, first prepare a batch and then wait for an available
	  server proof to have all work ready once the proof server is ready.
	- Remove the `isForgeSequence` method which was querying the smart
	  contract, and instead use notifications sent by the Synchronizer to
	  figure out if it's forging time.
	- Update test (which is a minimal test to manually see if the
	  coordinator starts)
- HistoryDB:
	- Add method to get the number of batches in a slot (used to detect when
	  a slot has passed the bid winner forging deadline)
	- Add method to get the best bid and associated coordinator of a slot
	  (used to detect the forgerAddress that can forge the slot)
- General:
	- Rename some instances of `currentBlock` to `lastBlock` to be more
	  clear.
- Node:
	- Connect the API to the node and call the methods to update cached
	  state when the sync advances blocks.
	- Call methods to update Coordinator state when the sync advances blocks
	  and finds reorgs.
- Synchronizer:
	- Add Auction field in the Stats, which contain the current slot with
	  info about highest bidder and other related info required to know who
	  can forge in the current block.
	- Better organization of cached state:
		- On Sync, update the internal cached state
		- On Init or Reorg, load the state from HistoryDB into the
		  internal cached state.

config/config.go

@@ -36,6 +36,7 @@ type ServerProof struct {
 type Coordinator struct {
 	ForgerAddress     ethCommon.Address `validate:"required"`
 	ForgeLoopInterval Duration          `validate:"required"`
+	ConfirmBlocks     int64             `validate:"required"`
 	L2DB              struct {
 		SafetyPeriod common.BatchNum `validate:"required"`
 		MaxTxs       uint32          `validate:"required"`
@@ -48,6 +49,16 @@ type Coordinator struct {
 		Path string `validate:"required"`
 	} `validate:"required"`
 	ServerProofs []ServerProof `validate:"required"`
+	EthClient    struct {
+		CallGasLimit        uint64   `validate:"required"`
+		DeployGasLimit      uint64   `validate:"required"`
+		GasPriceDiv         uint64   `validate:"required"`
+		ReceiptTimeout      Duration `validate:"required"`
+		IntervalReceiptLoop Duration `validate:"required"`
+	} `validate:"required"`
+	API struct {
+		Coordinator bool
+	} `validate:"required"`
 }
 
 // Node is the hermez node configuration.
@@ -78,12 +89,9 @@ type Node struct {
 		TokenHEZ     ethCommon.Address `validate:"required"`
 		TokenHEZName string            `validate:"required"`
 	} `validate:"required"`
-	EthClient struct {
-		CallGasLimit        uint64   `validate:"required"`
-		DeployGasLimit      uint64   `validate:"required"`
-		GasPriceDiv         uint64   `validate:"required"`
-		ReceiptTimeout      Duration `validate:"required"`
-		IntervalReceiptLoop Duration `validate:"required"`
+	API struct {
+		Address  string
+		Explorer bool
 	} `validate:"required"`
 	Debug struct {
 		APIAddress string