Reorganize smart contract types, udate eth tests, etc.

- Move smart contract constants and structs for variables to
  common/{ethrollup.go, ethauction.go, ethwdelayer.go}:
    - This removes repeated code of the structs for variables
    - Allows reusing the constants and variables from all modules without
      import cycles
- Remove unused common/scvars.go
- In common.BlockData, split data from each smart contract into a sepparate
  field (Rollup, Auction, WDelayer).  This affects the structures that til uses
  as output, and HistoryDB in the AddBlockSCData.
- In Synchronizer:
    - Pass starting block of each smart contract as config, instead of
      incorrectly using the genesis block found in the acution constant (which
      has a very different meaning)
    - Use variable structs from common instead of an internal copy
    - Synchronize more stuff (resolve some TODOs)
    - Fix some issues found after initial testing with ganache
- In eth:
    - In auction.go: Add method to get constants
    - Update README to use ganache instead of buidlerevm as local blockchain
      for testing
    - Update env variables and test vectors to pass the tests with the
      deployment in the ganache testnet.
    - Use ethereum keys derived from paths (hdwallet) in testing to avoid
      hardcoding private keys and generate the same keys from a mnemonic used
      in the ganache tesnet.

common/ethwdelayer.go

@@ -0,0 +1,24 @@
+package common
+
+import ethCommon "github.com/ethereum/go-ethereum/common"
+
+// WDelayerConstants are the constants of the Withdrawal Delayer Smart Contract
+type WDelayerConstants struct {
+	// Max Withdrawal Delay
+	MaxWithdrawalDelay uint64 `json:"maxWithdrawalDelay"`
+	// Max Emergency mode time
+	MaxEmergencyModeTime uint64 `json:"maxEmergencyModeTime"`
+	// HermezRollup smartcontract address
+	HermezRollup ethCommon.Address `json:"hermezRollup"`
+}
+
+// WDelayerVariables are the variables of the Withdrawal Delayer Smart Contract
+type WDelayerVariables struct {
+	HermezRollupAddress        ethCommon.Address `json:"hermezRollupAddress" meddler:"rollup_address"`
+	HermezGovernanceDAOAddress ethCommon.Address `json:"hermezGovernanceDAOAddress" meddler:"govdao_address"`
+	WhiteHackGroupAddress      ethCommon.Address `json:"whiteHackGroupAddress" meddler:"whg_address"`
+	HermezKeeperAddress        ethCommon.Address `json:"hermezKeeperAddress" meddler:"keeper_address"`
+	WithdrawalDelay            uint64            `json:"withdrawalDelay" meddler:"withdrawal_delay"`
+	EmergencyModeStartingTime  uint64            `json:"emergencyModeStartingTime" meddler:"emergency_start_time"`
+	EmergencyMode              bool              `json:"emergencyMode" meddler:"emergency_mode"`
+}