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/README.md

@@ -0,0 +1,37 @@
+# node cli
+
+This is the main cli for the node
+
+## Usage
+
+```
+NAME:
+   hermez-node - A new cli application
+
+USAGE:
+   node [global options] command [command options] [arguments...]
+
+VERSION:
+   0.1.0-alpha
+
+COMMANDS:
+   importkey  Import ethereum private key
+   wipesql    Wipe the SQL DB (HistoryDB and L2DB), leaving the DB in a clean state
+   run        Run the hermez-node in the indicated mode
+   help, h    Shows a list of commands or help for one command
+
+GLOBAL OPTIONS:
+   --mode MODE    Set node MODE (can be "sync" or "coord")
+   --cfg FILE     Node configuration FILE
+   --help, -h     show help (default: false)
+   --version, -v  print the version (default: false)
+```
+
+## Configuration
+
+You can find a testing working configuration example at
+[cfg.buidler.toml](./cfg.buidler.toml)
+
+To read the documentation of each configuration parameter, please check the
+`type Node` and `type Coordinator` at
+[config/config.go](../../config/config.go)