Add config flag to enable/disable meddler logs

- In config, add Debug.MeddlerLogs to enable meddler debug logs.  This only
  affects the node started via cli, tests swill ran with `meddler.Debug = true`
- Remove unused ethereum client functions and config parameters
- Document all the config parameters

cli/node/cfg.buidler.toml

@@ -11,6 +11,7 @@ Type = "bitfinexV2"
 
 [Debug]
 APIAddress = "localhost:12345"
+MeddlerLogs = true
 
 [StateDB]
 Path = "/tmp/iden3-test/hermez/statedb"
@@ -68,9 +69,6 @@ MaxTx = 512
 NLevels = 32
 
 [Coordinator.EthClient]
-CallGasLimit        = 300000
-DeployGasLimit      = 1000000
-GasPriceDiv         = 100
 ReceiptTimeout      = "60s"
 ReceiptLoopInterval = "500ms"